Disc recording medium, disc drive apparatus, and reproduction method

ABSTRACT

First data representing user data and third data use the same error correction codes. The first data has a first error correction block structure and the third data has a second error correction block structure. That is to say, the first data and the third data have their respective error correction block structures proper for them. In particular, the recording density of the third data is made less dense than the recording density of the first data, and the number of correction codes in the first error-correction block is set at a multiple of m whereas the number of correction codes in the second error-correction block is set at n/m times the number of correction codes in the first error-correction block so that a data-piece count in the second error-correction block is also n/m times a data-piece count in the first error-correction block. As a result, it is possible to provide a good technique of recording shipping-time information onto a high-recording-density disc.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and is based upon and claims thebenefit of priority under 35 U.S.C. §120 for U.S. Ser. No. 10/267,806,filed Oct. 9, 2002, and claims the benefit of priority under 35 U.S.C. §119 from Japanese Patent Application No. 2001-313819, filed Oct. 11,2001, the entire contents of each which are incorporated herein byreference.

BACKGROUND OF THE INVENTION

The present invention relates to a disc recording medium such as anoptical disc, a disc-manufacturing method for manufacturing the discrecording medium, a disc drive apparatus for driving the disc recordingmedium, and a reproduction method for reproducing data from the discrecording medium. More particularly, the present invention relates to adisc on which tracks are each wobbled as a pregroove.

As a technology of recording and reproducing digital data, there hasbeen developed a technology of recording data used in recording mediaonto optical discs including magneto-optical discs. An optical disc canbe designed as a CD (Compact Disc), an MD (Mini-Disc), or a DVD (DigitalVersatile Disc). The optical disc is a generic name of a disc-likemetallic thin plate serving as recording media from which data is readout as changes in reflected laser beam resulting from reflection of alaser beam radiated to the recording media.

To put it in more detail, an optical disc can be of a read-only type ora writable type allowing user data to be written onto the disc.Reproduction-only optical discs include a CD, a CD-ROM, and a DVD-ROM.On the other hand, writable optical discs include an MD, a CD-R, aCD-RW, a DVD-R, a DVD-RW, a DVD+RW, and a DVD-RAM. Data is recorded ontoa writable disc by adopting, among other techniques, a magneto-opticalrecording technique, a phase-change recording technique, and adye-film-change recording technique. The dye-film-change recordingtechnique is also referred to as a write-once recording techniquewhereby data can be recorded onto the optical disc only once, and oncedata has been recorded onto a disc, data can no longer be recorded ontothe same disc. Thus, the dye-film-change recording technique is suitablefor a recording operation to save data. On the other hand, themagneto-optical recording technique and the phase-change recordingtechnique are adopted in a variety of applications including operationsto record various kinds of content data such as musical data, videodata, games, and application programs.

In order to record data onto a disc to which the magneto-opticalrecording technique, the phase-change recording technique, and thedye-film-change recording technique are applicable, a guiding means fortracking a data track is required. For this reason, grooves are createdin advance as pregrooves. The grooves and lands are used as data tracks.A land is a plateau-like member sandwiched by two adjacent grooves.

In addition, it is also necessary to record address information so thatdata can be recorded at any predetermined position on a data track. Insome cases, however, the address information is recorded by wobbling thegrooves.

Assume that a track for recording data is created in advance as apregroove. In this case, the side walls of the pregroove each have awobbled shape representing address information.

By having such a pregroove, an address can be fetched from wobblinginformation obtained in recording and reproduction operations asinformation conveyed by a reflected beam. Thus, data can be recordedonto or reproduced from a desired location without creating for examplepit data showing addresses in advance.

By adding address information as a groove wobbling shape in this way, itis no longer necessary to provide for example discrete address areas onthe track and record addresses in the address areas typically as pitdata. Thus, portions for the address areas can be used for storingactual data so that the storage capacity can be increased.

It is to be noted that absolute-time information and addressinformation, which are each expressed by the groove wobbling shape assuch, are referred to as an ATIP (Absolute Time In Pregroove) and anADIP (Address In Pregroove) respectively.

By the way, in the case of a rewritable disc in particular, there may bea situation in which the manufacturer wants to ship a disc containingvarious kinds of shipping-time information recorded onto the disc inadvance. The shipping-time information of a disc is prerecordedinformation recorded onto the disc in advance prior to the shipping ofthe disc.

Typically, the shipping-time information includes disc information andsystem information. The disc information typically includes a recordinglinear velocity and a laser-power recommended value. On the other hand,the system information shows how to exclude an apparatus of a hacker.

The shipping-time information must be reliable, must have a large sizeto a certain degree, and must not be falsified.

If the shipping-time information is not reliable, that is, if the discinformation included in the shipping-time information is not accurate,for example, there may be raised a problem such as inability to obtain aproper recording condition in the apparatus on the user side.

In an operation to record content data, the data may be encrypted forprotection of a copyright. If a key used for encryption is not obtainedaccurately from the system information, the encrypted data cannot bedecrypted so that the content cannot be utilized. This is also becausethe content data cannot be encrypted in an operation to record the data.

For the reasons described above, disc information and systeminformation, which are recorded as shipping-time information, arerequired to have reliability higher than recorded and reproduced userdata.

The shipping-time information has a large size to a certain degreebecause of the following reasons.

Consider a case in which the master key of the system needs to beupdated because the key is leaked to a hacker. In this case, the type ofsystem (or product) or the like may be used as a unit of exclusion of ahacker apparatus. Thus, in order to update the master key, a largeamount of information to a certain degree is required as a bundle of keyinformation for identifying the master key for each unit. For thisreason, the system information inevitably has a comparatively largesize.

In addition, even if the possibility of existence of a defect such as aninjury or dirt on a disc is taken into consideration, it is important toread out the shipping-time information with a high degree of accuracyfrom the reliability point of view. For this reason, disc informationand system information are stored repeatedly. That is to say, the samedata is recorded a plurality of times. Naturally, the amount of theshipping-time information cannot but increase.

Falsification of information must be avoided because, if the systeminformation used for excluding an apparatus of a hacker as describedabove is not prevented from being falsified, the system information doesnot have a meaning. The function of the system information cannot beexecuted unless falsification of the system information is avoidedeffectively.

It is important for the shipping-time information as a prerecordedinformation to satisfy the above requirements. A recording techniquesuitable for the shipping-time information is also demanded.

It is to be noted that, as a method for prerecording the shipping-timeinformation onto a disc, a technique of creating embossed pits on thedisc is known.

If operations to record and reproduce high-density data onto and from anoptical disc are taken into consideration, however, theembossed-pit-prerecording technique has problems.

For operations to record and reproduce high-density data onto and froman optical disc, a groove with a small depth is required. In the case ofa disc manufactured by creation of grooves and embossed pits at the sametime by using a stamper, it is extremely difficult to form the groovesand the embossed pits with the depth of the grooves made different fromthe depth of the embossed pits. Thus, the depth of the grooves and thedepth of the embossed pits cannot help becoming equal to each other.

However, embossed pits with a small depth raises a problem that a signalhaving a high quality cannot be obtained from the embossed pits.

Assume for example that data having an amount of 23 GB (Giga Bytes) canbe recorded onto and reproduced from an optical disc with a diameter of12 cm and a cover (substrate) thickness of 0.1 mm through an opticalsystem employing a laser diode generating a laser having a wavelength of405 nm and an objective lens with an NA of 0.85 by recording andreproducing phase change marks at a track pitch of 0.32 μm and a lineardensity of 0.12 μm/bit.

In this case, the phase change marks are recorded onto and reproducedfrom a groove created to have a spiral shape on the disc. In order tosuppress media noises caused by the high density of the phase changemarks, it is desirable to create a groove with a depth of about 20 nm ofa depth in the range λ/13 to λ/12 where notation λ denotes a wavelength.

In order to obtain a signal from embossed pits having a high quality, onthe other hand, it is desirable to create a groove with a depth in therange λ/8 to λ/4. After all, it is impossible to get a good solution tothe problem of providing the same depth to the groove and the embossedpits.

From this situation, there has been demanded a method of prerecordingshipping-time information, which compensates embossed pits.

SUMMARY OF THE INVENTION

It is thus an object of the present invention addressing the problemsdescribed above to provide a new disc recording medium using anappropriate prerecording technique to increase the storage capacity ofthe disc recording medium and to improve the recording and reproductionperformance of the disc recording medium, provide a disc-manufacturingmethod for manufacturing the disc, provide a disc drive apparatus fordriving the disc recording medium as well as a reproduction method ofreproducing data from the disc recording medium.

In order to achieve the object described above, the present inventionprovides a disc recording medium including:

a recording/reproduction area, which first data can be recorded onto andreproduced from by adoption of a rewriting-capable recording techniqueand already recorded second data and, which second data remains recordedinto and reproduced from by adoption of a groove-wobbling technique; and

a reproduction-only area only allowing third data recorded therein byadoption of the groove-wobbling technique to be reproduced, wherein:

the first data is recorded by adoption of a first modulation techniqueand has a first error-correction block structure;

the second data is recorded by adoption of a second modulationtechnique; and

the third data is recorded by adoption of a third modulation techniqueand has a second error-correction block structure based on the samecorrection codes as those of the first error-correction block structure.

The first error-correction block includes a first frame structure, afirst sub-block structure including first error correction codes and asecond sub-block structure including second error correction codes. Onthe other hand, the second error-correction block includes a secondframe structure, a third sub-block structure including first errorcorrection codes and a fourth sub-block structure including second errorcorrection codes.

In addition, the second data and the third data are recorded along awobbling groove created in advance. The rewriting-capable recordingtechnique adopted for recording the first data is a recording techniqueof recording phase change marks onto a track implemented as the wobblinggroove described above.

As an alternative, the second data and the third data are recorded alonga wobbling groove created in advance whereas the rewriting-capablerecording technique adopted for recording the first data is a recordingtechnique of recording magneto-optical marks onto a track implemented asthe wobbling groove described above.

In addition, the third data recorded onto the reproduction-only areaincludes address information.

Furthermore, the recording density of the third data is made less densethan the recording density of the first data, and the number ofcorrection codes in the first error-correction block is set at amultiple of m whereas the number of correction codes in the seconderror-correction block is set at n/m times the number of correctioncodes in the first error-correction block so that a data-piece count inthe second error-correction block is also n/m times a data-piece countin the first error-correction block where notations n and m each denotea positive integer.

Moreover, the recording density of the third data is made less densethan the recording density of the first data, and the number of firstcorrection codes composing a first sub-block is set at a multiple of mwhereas the number of first correction codes composing a third sub-blockis set at n/m times the number of correction codes composing the firstsub-block so that a data-piece count in the third sub-block is also n/mtimes a data-piece count in the first sub-block where notations n and meach denote a positive integer.

In addition, the number of second correction codes composing a secondsub-block is set at a multiple of p, whereas the number of secondcorrection codes composing a fourth sub-block is set at q/p times thenumber of correction codes composing the second sub-block so that adata-piece count in the fourth sub-block is also q/p times a data-piececount in second sub-block where notations p and q each denote a positiveinteger.

In these cases, the integer m is a power of 2 and the integer n is 1.

Furthermore, the block lengths of the first error-correction block andthe second error-correction block are each set at such a value that theblock can be recorded in a circle of the track on the disc.

Moreover, the number of frames in the first error-correction block andthe number of frames in the second error-correction block are each setat a value at least about equal to a data-piece count in the errorcorrection codes.

In addition, the number of frames in the first error-correction blockand the number of frames in the second error-correction block can alsoeach be set at a value at least about equal to the sum of the number offirst correction code words and the number of second correction codewords.

Furthermore, the second frame includes a synchronization signal indata's portion corresponding to the third sub-block. The second framealso includes an address unit number in the data's portion correspondingto the fourth sub-block.

In addition, a frame for linking is added to the first error-correctionblock as well as to the second error-correction block.

As an alternative, a frame for linking is added to the firsterror-correction block but no frame for linking is added to the seconderror-correction block.

The first modulation technique described above is an RLL (1, 7) PPtechnique, the second modulation technique is an MSK modulationtechnique and the third modulation technique is a bi-phase modulationtechnique.

In addition, the first modulation technique can be the same as the thirdmodulation technique. In this case, the first and third modulationtechniques are both the RLL (1, 7) PP technique whereas the secondmodulation technique is the MSK modulation technique.

The present invention also provides a disc drive apparatus for recordingdata and reproducing data from a disc recording medium including:

a recording/reproduction area, which first data can be recorded onto andreproduced from by adoption of a rewriting-capable or write-oncerecording technique and, which second data remain recorded second intoand reproduced from by adoption of a groove-wobbling technique; and

a reproduction-only area only allowing third data recorded therein byadoption of the groove-wobbling technique to be reproduced, wherein:

the first data is recorded by adoption of a first modulation techniqueand has a first error-correction block structure;

the second data is recorded by adoption of a second modulationtechnique; and

the third data is recorded by adoption of a third modulation techniqueand has a second error-correction block structure based on the samecorrection codes as those of the first error-correction block structure.

Furthermore, the disc drive apparatus has:

head means for radiating a laser beam to a track created as the grooveand receiving a reflected beam signal;

wobbling extraction means for extracting a signal representing thewobbling shape of the track from the reflected beam signal;

first data-signal extraction means for extracting a signal representingthe first data from the reflected beam signal;

second data demodulation means for demodulating the signal representingthe wobbling shape of the track in a reproduction operation carried outon the recording/reproduction area by the second modulation technique;

first data demodulation means for demodulating the signal representingthe first data in a reproduction operation carried out on therecording/reproduction area by the first modulation technique;

third data demodulation means for demodulating, in a reproductionoperation carried out on the reproduction-only area, the signalrepresenting the wobbling shape of the track by the third modulationtechnique;

error correction means for carrying out error-correction processingbased on the error-correction codes on a modulation result output by thefirst data demodulation means and a modulation result output by thethird data demodulation means; and

control means for driving the second data demodulation means to carryout demodulation processing in a recording/reproduction operationperformed on the recording/reproduction area, requesting the errorcorrection means to carry out error-correction processing based on thefirst error correction block in a recording/reproduction operationperformed on the recording/reproduction area, driving the third datademodulation means to carry out demodulation processing in areproduction operation performed on the reproduction-only area,requesting the error correction means to carry out error-correctionprocessing based on the second error correction block in a reproductionoperation performed on the reproduction-only area.

In addition, the error correction means is capable of encoding anddecoding the first error correction block including a first framestructure, a first sub-block structure composed of first correctioncodes and a second sub-block structure composed of second correctioncodes, and capable of decoding the second error correction blockincluding a second frame structure, a third sub-block structure composedof first correction codes and a fourth sub-block structure composed ofsecond correction codes.

Moreover, the control means drives the head means to make an access tothe recording/reproduction area at a location indicated by addressinformation extracted as the second data and drives the head means tomake an access to the reproduction-only area at a location indicated byaddress information included in the third data.

In addition, the error-correction means carries out error correctionprocessing by setting the number of correction codes composing the firsterror correction block at a multiple of m and the number of correctioncodes composing the second error correction block at n/m times thenumber of correction codes composing the first error-correction blockwhere notations n and m each denote a positive integer.

Furthermore, the error-correction means carries out error correctionprocessing by setting the number of first correction codes composing thefirst error correction block at a multiple of m, the number of firstcorrection codes composing the third error correction block at n/m timesthe number of correction codes composing the first error-correctionblock where notations n and m each denote a positive integer, the numberof second correction codes composing the second error correction blockat a multiple of p and the number of second correction codes composingthe fourth error correction block at q/p times the number of correctioncodes composing the second error-correction block where notations p andq each denote a positive integer.

In these cases, the integer m is a power of 2 and the integer n is 1.

In addition, the demodulation processing is carried out by assuming thatthe first modulation technique described above is an RLL (1, 7) PPtechnique, the second modulation technique is an MSK modulationtechnique and the third modulation technique is a bi-phase modulationtechnique.

As an alternative, required demodulation processing is carried out byassuming that the first modulation technique is the same as the thirdmodulation technique.

As another alternative, demodulation processing is carried out byassuming that the first and third modulation techniques are both the RLL(1, 7) PP technique whereas the second modulation technique is an MSKmodulation technique.

The present invention also provides a reproduction method forreproducing data from a disc recording medium including:

a recording/reproduction area, which first data to be recorded onto andreproduced from by adoption of a rewriting-capable or write-oncerecording technique and, which second data remains recorded into andreproduced from by adoption of a groove-wobbling technique; and

a reproduction-only area only allowing third data recorded by adoptionof the groove-wobbling technique to be reproduced, wherein:

the first data is recorded by adoption of a first modulation techniqueand has a first error-correction block structure;

the second data is recorded by adoption of a second modulationtechnique; and

the third data is recorded by adoption of a third modulation techniqueand has a second error-correction block structure based on the samecorrection codes as those of the first error-correction block structure.

Furthermore, for a reproduction operation carried out on therecording/reproduction area, the reproduction method is further providedwith the steps of:

radiating a laser beam to a track created as the groove and receiving areflected beam signal;

extracting a signal representing the wobbling shape of the track and asignal representing the first data from the reflected beam signal;

demodulating the extracted signal representing the wobbling shape of thetrack by the second modulation technique and carrying a decoding processto produce address information;

demodulating the extracted signal representing the first data byadoption of a demodulation technique corresponding to the firstmodulation technique used for modulating the signal representing thefirst data; and

carrying out error-correction processing based on the error-correctioncodes of the first error correction block to reproduce the first data.

In addition, for a reproduction operation carried out on thereproduction-only area, the reproduction method is further provided withthe steps of:

radiating a laser beam to the track created as the groove and receivinga reflected beam signal;

extracting a signal representing the wobbling shape of the track fromthe reflected beam signal;

demodulating the extracted signal representing the wobbling shape of thetrack by the third modulation technique; and

carrying out error-correction processing based on the error-correctioncodes of the second error correction block to reproduce the third data.

In addition, for a reproduction operation carried out on therecording/reproduction area, the reproduction method is further providedwith the step of carrying out error correction processing based on thefirst error correction block including a first frame structure, a firstsub-block structure composed of first correction codes and a secondsub-block structure composed of second correction codes whereas, for areproduction operation carried out on the reproduction-only area, thereproduction method is further provided with the step of carrying outerror correction processing based on the second error correction blockincluding a second frame structure, a third sub-block structure composedof first correction codes and a fourth sub-block structure composed ofsecond correction codes.

Moreover, for a reproduction operation carried out on therecording/reproduction area, the reproduction method is further providedwith the step of making an access to the recording/reproduction area ata location indicated by address information extracted as the second dataand, for a reproduction operation carried out on the reproduction-onlyarea, the reproduction method is further provided with the step ofmaking an access to the reproduction-only area at a location indicatedby address information included in the third data.

In addition, in the error correction processing, the number ofcorrection codes composing the first error correction block is set at amultiple of m and the number of correction codes composing the seconderror correction block is set at n/m times the number of correctioncodes composing the first error-correction block where notations n and meach denote a positive integer.

Furthermore, in the error correction processing, the number of firstcorrection codes composing the first error correction block is set at amultiple of m, the number of first correction codes composing the thirderror correction block is set at n/m times the number of correctioncodes composing the first error-correction block where notations n and meach denote a positive integer, the number of second correction codescomposing the second error correction block is set at a multiple of pand the number of second correction codes composing the fourth errorcorrection block is set at q/p times the number of correction codescomposing the second error-correction block where notations p and q eachdenote a positive integer.

In these cases, the integer m is a power of 2 and the integer n is 1.

In addition, the demodulation processing is carried out by assuming thatthe first modulation technique described above is an RLL (1, 7) PPtechnique, the second modulation technique is an MSK modulationtechnique and the third modulation technique is a bi-phase modulationtechnique.

As an alternative, required demodulation processing is carried out byassuming that the first modulation technique is the same as the thirdmodulation technique.

As another alternative, demodulation processing is carried out byassuming that the first and third modulation techniques are both the RLL(1, 7) PP technique whereas the second modulation technique is an MSKmodulation technique.

In accordance with the present invention, on a disc of thewrite-once-storage-capacity type or a disc of the rewritable type,shipping-time information (prerecorded information) is recorded as thethird data by wobbling a groove. In processing to store the prerecordeddata, the recording density (and the recording technique as well as themodulation technique) are made less dense. In addition, error correctioncodes are used by adoption of the same technique as that forwrite-once-type data or rewritable-type data, which is handled as thefirst data. The amount of data per error correction block is alsoreduced to, for example, 1/m.

As a technique to record the first data (or user data) onto therecording/reproduction area, there is provided a phase-change recordingtechnique or a magneto-optical recording technique.

If the labor required at a disc-shipping time and the cost are to betaken into consideration, treatment as reproduction-only data created byusing a stamper is desirable since, in this case, it is not necessary torecord data of the shipping-time information as third data.

In addition, in a process to record pre-address information (ADIP) asthe second data, the groove is wobbled by using no pits. Thus, in thecase of a recorded disc of the write-once/rewritable type, pits are alsonot used in the shipping-time information so that a recording processcarried out by wobbling the groove is desirable.

The shipping-time information recorded as the third data has a necessaryproperty different from that of the pre-address information used as thesecond data.

That is to say, for the pre-address information recorded as the seconddata, the recording density may be low and a low error rate that can beassured by interpolative protection or the like is acceptable. Inaddition, if the second data is recorded in the recording/reproductionarea as a groove wobbling shape, the first data is superposed on thetrack implemented by the groove.

On the other hand, the shipping-time information can be recorded as thethird data at a recording density lower than that for the first data. Ifthe read time is to be taken into consideration, however, a recordingdensity about the same as that of the second data (that is, thepre-address information) will not work. In addition, an error rate notexceeding that of the first data is demanded. Furthermore, since thereproduction-only area for storing the shipping-time information is anarea created by using a stamper, that is, an area containing datarecorded as a groove wobbling shape, address information can be includedin the shipping-time information so that superposition on thepre-address information is not required.

It is thus possible to have a modulation technique for the third data(that is, the shipping-time information) different from that for thesecond data (or the ADIP).

Consider a case in which the third data is recorded by wobbling agroove. In a recording process carried out by wobbling a groove, ingeneral, the wobbling amplitude is small and the S/N (Signal-to-Noise)ratio of the signal is poor.

For this reason, in order to assure reliability of the third data (orthe shipping-time information), it is important to reduce the recordingdensity to a value much smaller than that of the first data.

In addition, the first data includes a relatively large error correctionblock (or strictly speaking, a relatively large first error correctionblock) including error correction codes, which are great in number fromthe error-correction-ability and redundancy points of view, andcompleting a deep interleaving process. By taking effects of dust andinjuries on the disc into consideration, however, the length of thefirst error correction block is set as large a value as possibleprovided that the value is within such a range that the block can berecorded without exceeding a circle of the track.

Also in an attempt to reduce the recording density of the third data,the third data is considered in the same way as the first data. That isto say, the second error correction block length of the third data isset at such a value that the block can be recorded without exceeding acircle of the track.

In addition, in an attempt to reduce the recording density of the thirddata, the first error correction block length of the first data is setat a value different from the second error correction block length ofthe third data.

Furthermore, the error correction codes of the third data are made thesame as the numerous error correction codes of the first data, which aregreat in number from the error-correction-ability and redundancy pointsof view.

Since it is undesirable to apply as many error correction codes aspieces of data in the frame associated with the error correction codes,the data-piece count in a frame is made about equal to or smaller thanthe number of interleaves, that is, the number of codes.

Thus, as the size of the first error correction block is made differentfrom the size of the second error correction block, the frame structurechanges.

In the case of the first data, the first error correction block includesm error correction codes. When the sizes of the error correction blocksfor the first data and the third data are changed to accompany reductionof the recording density of the third data, the second error correctionblock for the third data is constructed from n/m error correction codes.

In this case, it is desirable to set an effective-data-piece count ofthe first error correction block at a multiple of a power of 2 such as amultiple of 2,048 bytes.

In addition, it is also desirable to set an effective-data-piece countof the second error correction block for the third data at a multiple ofa power of 2 such as a multiple of 2,048 bytes.

If an EDC (Error Detection Code) or the like is added, theeffective-data-piece count may become a value different from a power of2 in some cases. In order to have both an effective-data-piece count ofthe first error correction block and an effective-data-piece count ofthe second error correction block equal to a multiple of a power of 2,it is necessary to set the value of m at a power of 2 as well.

Furthermore, if both the effective-data-piece count of the first errorcorrection block and the effective-data-piece count of the second errorcorrection block are equal to a power of 2, that is, if n=1, accesses todata can be made with ease.

If the frame structure of the third data (that is, the shipping-timeinformation) is changed to the frame structure of the first data (thatis, the user data), the way to insert a synchronization signal, a DCcontrol signal (or the so-called dcc) and the like also changes as well.

In the case of the third data, it is not necessary to considersuperposition of the second data (that is, the pre-address information)as is the case with the first data. In addition, a recording density ashigh as that of the first data is also not required. For these reasons,a simple modulation method can be adopted as the modulation technique ofthe third data.

If the conditions described above do not exist, on the other hand, thesame modulation method as that of the first data can be adopted as themodulation technique of the third data.

Since the third data recorded as a groove wobbling shape is formed inadvance by using a stamper, address information can be recorded too atthe same time so that the disc drive apparatus is capable of making anaccess by using the address information.

In this case, a sync pattern and a sync ID are provided on a portion ofthe frame of the third data while an address unit number is provided ona certain portion of the frame.

Since pre-address information is recorded in the recording/reproductionarea in advance as the second data, an access can actually be made evenif only a minimum sync pattern exists. Nevertheless, the sync pattern,the sync ID and the address unit number do not cause a problem even ifthey are provided.

In addition, since the first data is data to be rewritten, framestypically referred to as run-in and run-out frames are requiredrespectively in front of and behind a cluster serving as a rewrite unit.The run-in and run-out frames are used for linking. For example, therun-in frame in front of a specific cluster includes an APC operationarea for laser power control, a VFO pattern for PLL leading-in, a syncpattern for synchronization leading-in and a gap area between thespecific cluster and a cluster immediately preceding the specificcluster. On the other hand, the run-out frame typically includes apost-amble pattern and a gap area.

Since no other data is recorded onto the reproduction-only area, whichis used for recording the third data, however, the APC area, the gaparea and the like are not required. In addition, since a data seriesincluding synchronization information and address information is createdcontiguously by using a stamper, the VFO pattern for PLL leading-in isalso not required either. Thus, even without the run-in frame, framesynchronization, synchronization based on frame numbers and even addresssynchronization can be established.

In addition, since the following cluster also starts immediately, thedata series is continuous and a post-amble, that is, a run-out frame, isnot required either.

Thus, in the case of the third data recorded in the reproduction-onlyarea, the linking frames known as the run-in and run-out frames can beeliminated.

As is comprehensible from the description described above, in accordancewith the present invention, with a recording technique, a modulationtechnique and a recording density optimumly applied to the first data,the second data and the third data as they are, it is possible toimplement a write-once-type or rewritable-type disc having a largecapacity for recording user data as the first data and properly recordshipping-time information serving as third data.

That is to say, the present invention exhibits an effect that it ispossible to record a proper amount of third data serving as prerecordedinformation or the shipping-time information that cannot be falsified byat sustained high reliability.

In addition, in the case of the disc provided by the invention, theeffect on devices and circuits employed in the disc drive apparatus issmall so that a simple configuration can be realized without incurringan increase in cost.

To put it in detail, the present invention exhibits the followingeffects.

The first data and the third data share the same error correction codes.Thus, the first data and the third data can be subjected to an ECCprocess carried out by common hardware allowing the cost of the discdrive apparatus to be lowered and the configuration of the apparatus tobe simplified.

Furthermore, the first data has a first error correction block structurewhile the third data has a second error correction block structure. Thatis to say, the first data and the third data have their respectiveproper error correction block structures.

In particular, the recording density of the third data is made lessdense than the recording density of the first data, and the number ofcorrection codes in the first error-correction block is set at amultiple of m, whereas the number of correction codes in the seconderror-correction block is set at n/m times the number of correctioncodes in the first error-correction block, and the number of data in thesecond error-correction block is set at n/m times the number of data inthe first error-correction block, so that not only do the first data andthe third data have their respective proper error correction blockstructures, but the error correction structures are also amenable toerror correction processing.

Moreover, even if the first error-correction block includes a firstframe structure, a first sub-block structure including first errorcorrection codes such as LDC and a second sub-block structure includingsecond error correction codes such as BIS while the seconderror-correction block includes a second frame structure, a thirdsub-block structure including first error correction codes such as LDCand a fourth sub-block structure including second error correction codessuch as BIS, the first data and the third data share the same errorcorrection codes, and in addition, the first data and the third datahave their respective proper error correction blocks.

Particularly, in this case, the recording density of the third data ismade less dense than the recording density of the first data, the numberof first correction codes composing a first sub-block is set at amultiple of m whereas the number of first correction codes composing athird sub-block is set at n/m times the number of correction codescomposing the first sub-block, and in addition, the number of secondcorrection codes composing a second sub-block is set at a multiple of p,whereas the number of second correction codes composing a fourthsub-block is set at q/p times the number of correction codes composingthe second sub-block so that not only do the first data and the thirddata have their respective proper error correction block structures, butthe error correction structures are also amenable to error correctionprocessing.

In these cases, the optimum values of the integers m and n are a powerof two and one respectively.

Moreover, the reproduction-only area is used as an area for recordingthe third data by groove wobbling. It is thus no longer necessary torecord the third data by using embossed pits. Then, since it is notnecessary to create embossed pits, the depth of the groove can bereduced. The depth of the groove can be set at a value optimum for ahigh recording density without taking the reproduction characteristicsof the embossed pits into consideration. Thus, it is possible to providea groove proper for a high recording density.

In addition, in the disc drive apparatus, the third data can bereproduced by using the same wobble-channel reproduction system as thesecond data or the ADIP address information. Reproduction of the thirddata means extraction of information on the wobbling shape of the groovealong which the third data is recorded.

Furthermore, since the recording density of the third data recorded asthe wobbling shape of the groove can be made less dense than therecording density of the first data, the third data can be reproduced ata high quality even though its SNR is poor due to the fact that thethird data is reproduced as a wobbling signal.

Moreover, the third data is recorded after completing a bi-phasemodulation process such as the FM code modulation process. Thus, thesignal can be treated as a narrow-band signal, allowing the SNR to beimproved. In addition, the PLL and detection circuits can each bedesigned as simple hardware.

As an alternative, the third data is modulated by adoption of the sametechnique as the first data. Even in this case, a common demodulationcircuit configuration can be shared between the first data and the thirddata so that the disc drive apparatus can be simplified.

Furthermore, the third data includes address information. Thus, the discdrive apparatus is capable of properly making accesses to thereproduction-only area and appropriately carrying out operations toreproduce data from the reproduction-only area on the basis of theaddresses included in the third data.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are explanatory diagrams each showing a groove createdon a disc implemented by an embodiment of the present invention;

FIG. 2 is an explanatory diagram showing an area configuration of theentire disc implemented by the embodiment;

FIGS. 3A and 3B are explanatory diagrams each showing a wobblingtechnique adopted for a groove created on the disc implemented by theembodiment;

FIG. 4 is an explanatory diagram showing ECC block and data framesstructures recorded as phase change marks in the embodiment;

FIGS. 5A to 5C are explanatory diagrams showing ECC block structuresrecorded as phase change marks in the embodiment;

FIG. 6 is an explanatory diagram showing a RUB frame structure of phasechange marks in the embodiment;

FIGS. 7A to 7C are explanatory diagrams showing a technique ofmodulating ADIP information in the embodiment;

FIGS. 8A and 8B are explanatory diagrams showing of address blocks in aRUB in the embodiment;

FIGS. 9A and 9B are explanatory diagrams showing a sync part in theembodiment;

FIGS. 10A to 10E are explanatory diagrams showing sync bit patterns inthe embodiment;

FIGS. 11A to 11B are explanatory diagrams showing a data part in theembodiment;

FIGS. 12A to 12C are explanatory diagrams showing ADIP bit patterns inthe embodiment;

FIG. 13 is an explanatory diagram showing the ECC structure of ADIPinformation in the embodiment;

FIGS. 14A to 14K are explanatory diagrams showing a method of modulatingprerecorded information in the embodiment;

FIG. 15 is an explanatory diagram showing an ECC block of prerecordedinformation and data frames of the embodiment;

FIGS. 16A to 16D are explanatory diagrams showing ECC block structuresof prerecorded information in the embodiment;

FIG. 17 is an explanatory diagram showing the frame structure of acluster of prerecorded information in the embodiment;

FIG. 18 is an explanatory diagram showing the frame structure of acluster of prerecorded information in the embodiment;

FIG. 19 is an explanatory diagram used for describing a process toconvert a data series of an LDC sub-block in the embodiment;

FIG. 20 is an explanatory diagram used for describing a process toconvert a data series of an LDC sub-block in the embodiment;

FIG. 21 is an explanatory diagram used for describing a process toconvert a data series of an LDC sub-block in the embodiment;

FIGS. 22A and 22B are explanatory diagrams showing the configuration ofa BIS sub-block in the embodiment;

FIG. 23 is an explanatory diagram used for describing a process toconvert a data series of a BIS sub-block in the embodiment;

FIG. 24 is an explanatory diagram used for describing a process toconvert a data series of a BIS sub-block in the embodiment;

FIG. 25 is an explanatory diagram used for describing a process toconvert a data series of a BIS sub-block in the embodiment;

FIG. 26 is an explanatory diagram used for describing the framestructure, which is carried out when data of LDC and BIS sub-blocks isrecorded onto a disc;

FIG. 27 is an explanatory diagram showing an ECC block of prerecordedinformation and data frames of the embodiment;

FIG. 28 is an explanatory diagram showing the frame structure of acluster of prerecorded information in the embodiment;

FIG. 29 is an explanatory diagram showing the frame structure of acluster of prerecorded information in the embodiment;

FIG. 30 is an explanatory diagram showing frame synchronizations ofprerecorded information in the embodiment;

FIG. 31 is an explanatory diagram showing a layout of framesynchronizations of prerecorded information in the embodiment;

FIG. 32 is a block diagram showing a typical configuration of a discdrive apparatus provided by the embodiment;

FIG. 33 is a block diagram showing a typical configuration of a wobblecircuit employed in the disc drive apparatus provided by the embodiment;and

FIG. 34 is a block diagram showing a typical configuration of a cuttingapparatus for manufacturing the disc implemented by the embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Next, an optical disc implemented by an embodiment of the presentinvention, a disc drive apparatus (or a recording/reproductionapparatus) for the optical disc, and a method of manufacturing theoptical disc are explained in paragraphs arranged in an order shownbelow.

The optical disc implemented by the embodiment is known typically as aDVR (Data & Video Recording) disc and belongs to a category of discsdeveloped in recent years.

1. Overview of an Embodiment Implementing a DVR Disc Provided by theInvention 2. Physical Characteristics of the Disc 3. ECC Block Structureof User Data 4. ADIP Addresses 5. Prerecorded Information (Shipping-TimeInformation) 6. Disc Drive Apparatus 7. Disc-Manufacturing Method 8.Modified Versions 1. Overview of an Embodiment Implementing a DVR DiscProvided by the Invention

First of all, the following description shows how technical words usedin claims of the present invention are associated with technical wordsused in explanation of an embodiment implementing a DVR system. It isneedless to say that the meanings of the technical words used in theclaims of the present invention are not limited to the meanings of thetechnical words used in the explanation of the embodiment.

First data used in claims corresponds to user data used in theexplanation of the embodiment. The user data is main data serving as aprinciple object of recording and reproduction. The user data isrecorded in a recording/reproduction area as phase change marks.

Second data used in claims corresponds to an ADIP used in theexplanation of the embodiment. The ADIP is pre-address informationrecorded in the form of groove wobbling in a recording/reproductionarea.

Third data used in claims corresponds to shipping-time information usedin the explanation of the embodiment. The shipping-time information isprerecorded information recorded in the form of groove wobbling in thereproduction-only area.

A first modulation technique used in claims corresponds to an RLL (1, 7)PP technique used in the explanation of the embodiment.

A second modulation technique used in claims corresponds to an MSKmodulation technique used in the explanation of the embodiment.

A third modulation technique used in claims corresponds to a bi-phasemodulation technique used in the explanation of the embodiment.

A correction code used in claims corresponds to an LDC (Long DistanceCode) and a BIS (Burst Indicating Sub code) used in the explanation ofthe embodiment.

A first correction code used in claims corresponds to the LDC (LongDistance Code).

A second correction code used in claims corresponds to the BIS.

An error correction block used in claims corresponds to an ECC blockusing LDC and BIS as described in the explanation of the embodiment.

First and Third sub-blocks used in claims correspond to an LDC sub-blockused in the explanation of the embodiment.

Second and forth sub-blocks used in claims correspond to a BIS sub-blockused in the explanation of the embodiment.

A data block of user data recorded in a DVR disc as phase-change marksincludes a sub-block of actual data and a sub-block of user controldata. By the actual data, the user data is meant. The user control datais addition & control information provided for the user data. Addressinformation provided in data separately from the pre-address informationreferred to as the ADIP can also be included as part of the addition &control information.

In order to assure the ability to correct errors in the entire datablock, error correction codes required for the sub-blocks are used.Details of this matter will be described later.

That is to say, for the user data, an LDC sub-block is created toinclude LDC each used as an error correction code. For the user controldata, on the other hand, a BIS sub-block is created to include BIS eachused as an error correction code.

A data frame is created to compress pieces of data for which an LDCsub-block and a BIS sub-block are created.

Since it is undesirable to apply as many error correction codes aspieces of data in a data frame for which LDC and BIS sub-blockscontaining the error correction codes are created, the data-piece countin the data frame is made about equal to or smaller than a sum ofinterleave counts of the error correction codes or a sum of code counts.

By the same token, a data block of shipping-time information includes asub-block of prerecorded data and a sub-block of prerecorded controldata. The prerecorded data is actual data prerecorded as shipping-timeinformation. On the other hand, the prerecorded control data is addition& control information prerecorded for the shipping-time information.

In order to assure the ability to correct errors in the entire datablock, error correction codes required for the sub-blocks are used. Thatis to say, in this embodiment, for the actual data prerecorded asshipping-time information, an LDC sub-block is created to include LDCeach used as an error correction code. For the prerecorded control data,on the other hand, a BIS sub-block is created to include BIS each usedas an error correction code.

Also in the case of a block of the shipping-time information, a dataframe is created to compress pieces of data for which an LDC sub-blockand a BIS sub-block are created. In addition, the data-piece count inthe data frame is made about equal to or smaller than a sum ofinterleave counts of the error correction codes or a sum of code counts.

In a few words, the sub-blocks of actual data share the same errorcorrection codes, namely, the LDC, regardless of whether the actual datais user data or prerecorded data. On the other hand, the sub-blocks ofaddition & control information share the same error correction codes,namely, the BIS, without regard to whether the addition & controlinformation is user control data or prerecorded control data.

In accordance with this technique, an actual-data sub-block in a blockof user data includes m LDC error correction codes. In an attempt tomake the size of a block of data prerecorded as shipping informationdifferent from the size of a block of user data to accompany reductionof the recording density of the data prerecorded as shipping-timeinformation, an actual-data sub-block in a block of prerecorded data iscreated to include n/m LDC error correction codes.

In this case, it is desirable to set the effective data piece count ofthe actual-data sub-block in a block of user data at a multiple of apower of two such as 2,048 bytes.

Likewise, it is desirable to set the effective data piece count of theactual-data sub-block in a block of data prerecorded as theshipping-time information also at a multiple of a power of two such as2,048 bytes.

If an EDC or the like is added, the effective data piece count maybecome equal to a value other than a power of two in some cases.Nevertheless, in order to have both the effective data piece count ofthe actual-data sub-block in a block of user data and the effective datapiece count of the actual-data sub-block in a block of data prerecordedas the shipping-time information equal to a multiple of a power of two,it is necessary for the value of m to be equal to a power of two.

In addition, if both the effective data piece count of the actual-datasub-block in a block of user data and the effective data piece count ofthe actual-data sub-block in a block of data prerecorded as theshipping-time information are equal to a power of two, that is, n=1, anaccess to the data can be made with ease.

An addition & control-information sub-block in a block of user dataconstitutes p BIS error correction codes. In an attempt to change thesize of a block of data prerecorded as shipping information and the sizeof a block of user data to accompany reduction of the recording densityof the data prerecorded as shipping-time information, an actual-datasub-block in a block of data prerecorded as the shipping-timeinformation is created to constitutes q/p BIS error correction codes.

Since the addition & control information is merely information providedfor actual data, it not necessary to set the value of p at a power oftwo and q=1.

Since data is created in the reproduction-only area used for recordingthe shipping-time information by using a stamper, address informationcan be recorded at the same time as part of the shipping-timeinformation. Thus, the disc drive apparatus is capable of making anaccess by using this address information.

An sync pattern and a sync ID are provided on a portion of the frame ofthe shipping-time information while an address unit number is providedon a certain portion of the frame.

To be more specific, in a DVR system, a sync pattern and a sync ID areprovided in a portion of data corresponding to an actual-data sub-blockin a frame of shipping-time information whereas an address unit numberis provided in a portion of data corresponding to an addition & controlsub-block in the frame of shipping-time information.

Since pre-address information (or an ADIP) is recorded in advance in therecording/reproduction area for recording user data, an access canactually be made even if only a minimum sync pattern exists.Nevertheless, the sync pattern, the sync ID, and the address unit numberdo not cause a problem even if they are provided.

In addition, for the user data, frames typically referred to as run-inand run-out frames are required respectively in front of and behind acluster serving as a rewrite unit. The run-in and run-out frames areused for linking. The run-in frame in front of a specific clusterincludes an APC operation area for laser power control, a VFO patternfor PLL leading-in, a sync pattern for synchronization leading-in, and aGAP area between the specific cluster and a cluster immediatelypreceding the specific cluster. On the other hand, the run-out frametypically includes a post-amble pattern and a GAP area.

Since no other data is recorded onto the reproduction-only area, whichis used for recording the shipping-time information, however, the APCarea, the GAP area and the like are not required. In addition, since adata series including synchronization information and addressinformation is created contiguously by using a stamper, the VFO patternfor PLL leading-in is also not required either. Thus, even without therun-in frame, frame synchronization, synchronization based on framenumbers and even address synchronization can be established.

In addition, since the following cluster also starts immediately, thedata series is continuous, and a post-amble, that is a run-out frame, isnot required either.

Thus, in the case of the shipping-time information recorded in thereproduction-only area, the linking frames known as the run-in andrun-out frames can be eliminated.

2. Physical Characteristics of the Disc

The embodiment is explained concretely as follows.

First of all, physical characteristics of the disc implemented by theembodiment and a wobbling track created on the disc are described.

The optical disc implemented by the embodiment is known typically as aDVR (Data & Video Recording) disc and belongs to a category of discsdeveloped in recent years. In particular, a new wobbling technique isapplied to the optical disc as a DVR technique.

The optical disc implemented by the embodiment is an optical disc ontowhich data is recorded by adoption of a phase change technique. As forthe size of the optical disc, the disc has a diameter of 120 mm and athickness of 1.2 mm. From the external-appearance point of view, theoptical disc implemented by the embodiment is the same as a disc of a CD(Compact Disc) system or a disc of a DVD (Digital Versatile Disc) systemas far as the diameter and the thickness are concerned.

A laser beam for recording and reproduction of data has a wavelength of405 nm. The laser beam is the so-called blue-color laser. The NA of theoptical system is set at 0.85.

Tracks along which phase change marks are recorded have a track pitch of0.32 μm and a linear density of 0.12 μm.

A user-data storage capacity of about 23 Gbyte has been realized.

A groove recording technique is adopted as a recording technique. Thatis to say, a track is created as a groove in advance on the disc anddata is recorded along this groove.

FIG. 1A is an explanatory diagram showing a model of a groove GV createdon a disc. As shown in the figure, the groove GV is created to form aspiral-like shape over the disc's surface spread from the innermostcircumference to the outermost circumference. As an alternative, thegroove GV can be created to form a concentric shape.

Data is recorded and reproduced while the disc is rotating at a CLV(Constant Linear Velocity). Thus, since the groove GV is also rotated atthe CLV, the number of wobbling waves per track circle increases ifviewed at a point moving in a radial direction from the innermostcircumference to the outermost circumference.

FIG. 1B is an explanatory diagram showing grooves GV each having awobbling shape expressing physical addresses.

As shown in the figure, the left and right side walls of the groove GVare wobbled to represent a signal generated on the basis of addresses orthe like.

A land L is a gap between two adjacent grooves GV. As described above,data is recorded along a groove GV. That is to say, a groove GV is adata track. It is to be noted that data can also be recorded along aland L. In this case, a land L is a data track. As another alternative,data is recorded along a groove GV as well as a land L, which are bothdata tracks in this case.

FIG. 2 is an explanatory diagram showing a layout or an areaconfiguration of the entire disc.

The area on the disc is physically divided sub-areas called, startingfrom the inner side, a lead-in zone, a data zone, and a lead-out zone.

From a functional point of view, on the other hand, the surface of thedisc is divided into a PB zone (or a reproduction-only area) and an RWzone (or a recording/reproduction area). The PB zone is theinner-circumferential side of the lead-in zone, and the RW zone is anarea stretched from the outer-circumferential side of the lead-in zoneto the lead-out zone.

The lead-in zone is an inner side zone inside a circumference with aradius of 24 mm. A prerecorded data zone is the lead-in zone's areabetween a circumference with a radius of 22.3 mm and a circumferencewith a radius of 23.1 mm.

The prerecorded data zone is used for recording shipping-timeinformation (or prerecorded information) in advance as a wobbling shapeof a groove created on the disc as a spiral. The shipping-timeinformation is reproduction-only information, which cannot be rewritten.The prerecorded data zone is the PB zone (or the reproduction-only area)cited above.

The lead-in zone's area between a circumference with a radius of 23.1 mmand a circumference with a radius of 24 mm is used as a test write areaand a defect management area.

The test write area is used typically as a trial write area for settingconditions for recording and reproduction of phase change marks. Theconditions include the power of a laser beam used in recording andreproduction operations.

The defect management area is used for recording and reproduction datafor managing information on defects existing on the disc.

A zone between a circumference with a radius of 24.0 mm and acircumference with a radius of 58.0 mm is a data zone. The data zone isan area, which user data is actually recorded onto and reproduced fromas phase change marks.

A zone between a circumference with a radius of 58.0 mm and acircumference with a radius of 58.5 mm is the lead-out zone. Much likethe lead-in zone, the lead-out zone includes a defect management areaand a buffer area allowing an overrun to occur in a seek operation.

An area stretched from the circumference with a radius of 23.1 mm, thatis, the start of the test write area, to the lead-out zone is the RWzone (or the recording/reproduction area) cited above.

FIG. 3 is explanatory diagrams showing respectively a track used as theRW zone and a track used as the PB zone. To be more specific, FIG. 3A isa diagram showing the wobbling shape of a groove in the RW zone, andFIG. 3B is a diagram showing the wobbling shape of a groove in the PBzone.

In the RW zone, address information (or an ADIP) is recorded in advanceby wobbling the groove created on the disc to form a spiral shape for atracking purpose.

Information is recorded onto and reproduced from the groove, whichincludes the embedded address information by phase change marks.

As shown in FIG. 3A, the groove in the RW zone, that is, the groovetrack including the embedded ADIP address information, has a track pitchTP of 0.32 μm.

On this track, phase change marks each serving as a recording mark arerecorded. By adoption of a RLL (1, 7) PP modulation technique or thelike, the phase change marks are recorded at a linear density of 0.12μm/bit or 0.08 μm/channel bit. The RLL stands for Run Length Limited andthe PP is an abbreviation of Parity preserve/Prohibit rmtr (repeatedminimum transition run length).

Let 1 T represent one channel bit. In this case, the mark length is avalue in the range 2 T to 8 T. That is to say, the minimum mark lengthis 2 T.

As described above, the address information is recorded as the groove'swobbling shape with a wobbling period of 69 T and a wobbling amplitudeWA of about 20 nm (peak to peak).

The frequency band of the address information is set not to overlap thefrequency band of the phase change marks so that there is no mutualeffect on detection of the address information and the phase changemarks.

At a bandwidth of 30 KHz, the address information recorded as a wobblingshape has a post-recording CNR (Carrier Noise Ratio) of 30 dB and anaddress error rate not greater than 1×10⁻³. The address error rate isobtained by consideration of effects caused by disturbances such a discskew, a defocused state, and an external turbulence

On the other hand, a track created as the groove in the PB zone shown inFIG. 3B has a track pitch greater than that of the track created as thegroove in the RW zone shown in FIG. 3A, and a wobbling amplitude is alsogreater than that of the track created as the groove in the RW zoneshown in FIG. 3A.

To out it concretely, the track shown in FIG. 3B has a track pitch TP of0.35 μm, a wobbling period of 36 T and a wobbling amplitude WA of 40 nm(peak to peak). The wobbling period of 36 T implies that the linearrecording density of the prerecorded information is higher than thelinear recording density of the ADIP address information. In addition,since the minimum mark length of the phase change marks is 2 T, thelinear recording density of the prerecorded information is lower thanthe linear recording density of phase change marks.

The track in the PB zone is not used for recording phase change marks.

The wobbling waveform expressing recorded data in the RW zone issinusoidal, but the wobbling waveform expressing recorded data in the PBzone is sinusoidal or rectangular.

In an operation to record or reproduce phase change marks with ECC(Error Correction Codes) appended to the data, a post-error-correctionsymbol error rate of 1×10⁻¹⁶ can be achieved provided that the signalhas a high quality such as a CNR of 50 dB at a bandwidth of 30 KHz.Thus, the phase change marks have been known to be usable in anoperation to record or reproduce data.

The wobbling CNR of the ADIP address information is 35 dB at a bandwidthof 30 KHz in a state of unrecorded phase change marks.

As address information, the signal quality of this order is consideredto be sufficient if interpolation protection based on the so-calledcontiguity distinction is carried out. In the case of the prerecordedinformation to be stored in the PB zone, however, it is desirable toassure a signal quality equivalent to or better than a CNR of 50 dB forthe phase change marks. For this reason, in the PB zone, a groovephysically different from the groove in the RW zone as shown in FIG. 3Bis created.

In the first place, by increasing the track pitch, cross talks fromadjacent tracks can be suppressed. In the second place, by doubling thewobbling amplitude, the CNR can be improved by +6 dB.

In addition, by forming a rectangular wobbling waveform, the CNR can befurther improved by +2 dB. These combined improvements result in a CNRof 43 dB (=35 dB+6 dB+2 dB).

The difference in wobbling recording band between the zone for storingthe phase change marks and the zone for storing the prerecorded data iswobbling period of 18 T, which is half the wobbling period of 36 T. Atthe 2 T minimum mark length of the phase change marks, another CNRimprovement of 9.5 dB is gained.

As a result, the CNR of the prerecorded information is equivalent to52.5 dB (=43 dB+9.5 dB). Thus, even if the cross talks from the adjacenttracks are estimated to give a CNR deterioration of −2 dB, the CNR isstill equivalent to 50.5 dB (=52.5 dB−2 dB). That is to say, it ispossible to assure a signal quality equivalent to or better than the CNRof 50 dB for the phase change marks so that the wobbling signal can besaid to be a sufficiently suitable signal to be used in operations torecord and reproduce the prerecorded information.

3. ECC Block Structure of User Data

An ECC block structure of user data recorded in the RW zone (or therecording/reproduction area) as phase change marks is explained byreferring to FIG. 4.

A data block of user data physically constitutes roughly 32 sectors.From a content point of view, the data block includes a sub-block ofuser data and a sub-block of user control data.

As shown in FIG. 4, the sub-block of user data forms the unit having asize of 64 Kbytes (=2,048 bytes×32 sectors).

A 4 bytes EDC (Error Detection Code) is added to each sector to form adata frame unit. 32 data frame units form a data frame having a size of2,052 bytes×32 sectors. The data frame is further scrambled to produce ascrambled data frame.

Then, the scrambled data frame is subjected to a Reed-Solomon encodingprocess to generate a data block of 216 rows and 304 columns. Thirty-tworows of parity are further added to the data block to generate an LDC(Long Distance Code) sub-block. The LDC is a correction code for a longinter-code distance. The LDC sub-block is an RS (248, 216, 33)×304block.

Then, an LDC cluster of 496 rows×152 bytes is formed from the LDCsub-block.

FIGS. 5A and 5B are diagrams showing a process to encode the sub-blockof user data into the LDC sub-block.

The 64 Kbytes user data shown in FIG. 5A is subjected to an ECC encodingprocess to produce the LDC sub-block shown in FIG. 5B. To put it indetail, a 4 bytes EDC (Error Detection Code) is added to each 2,048bytes sector of the main data (the user data). The 32 sectors of theuser data are then encoded into an LDC sub-block. As mentioned above,the LDC sub-block is an RS (Reed Solomon) code with an RS (248, 216,33), a code length of 248 nibbles, a data size of 216 nibbles, a codedistance of 33 nibbles, and has a block size of 304 code words.

On the other hand, the sub-block of user control data has a size of 18bytes×32 units (576 bytes) as shown in FIG. 4. Address unit numbershaving a size of 9 bytes×16 addresses (144 bytes) are added to thesub-block of user control data to generate an encoding unit having asize of 720 bytes (=576 bytes+144 bytes).

The 720 bytes are subjected to the Reed Solomon encoding process toproduce an access block of 30 rows×24 columns.

Then, 32 rows of parity are added to form a BIS (Burst Indicating Subcode) sub-block. A BIS is a sub code indicating the position of a bursterror of an optical disc. The BIS sub-block is an RS (62, 30, 33)×24block. Then, a BIS cluster of 496 rows×3 bytes is formed from the BISsub-block.

FIGS. 5C and 5D are diagrams showing a process to encode the usercontrol data and the address unit number, which have a total size of 720bytes, into the BIS sub-block.

That is to say, the 720 bytes of data shown in FIG. 5C are subjected toan ECC encoding process to generate the BIS sub-block shown in FIG. 5D.As mentioned above, the BIS sub-block is the RS (Reed Solomon) code withand RS (62, 30, 33), a code length of 62 nibbles, a data size of 30nibbles, a code distance of 33 nibbles, and has a block size of 24 codewords.

As shown in FIG. 4, the LDC and BIS clusters, which are each used as arecording/reproduction unit, each forms 496 rows each constituting adata frame. A data frame of the LDC cluster forms 152 bytes while a dataframe of the BIS cluster forms 3 bytes.

Thus, a combined data frame forms 155 bytes (=152 bytes+3 bytes). Asshown in the figure, in the combined data frame, four LDC fields eachhaving a size of 38 bytes and three BIS fields each having a size of 1byte are arranged alternately to form the 155 bytes data frame on onerow. 496 rows or 496 data frames each having a size of 155 bytes (=1,240bits) constitute an ECC block.

Each of the data frames is subjected to an RLL (1, 7) PP modulationprocess, in which dcc bits and a frame sync are added to generate arecording frame. A dcc bit is a bit for making the frame free from DCcomponents. To put it in detail, data (1,240 bits) obtained as a resultof the modulation process is divided into that a start group placed atthe beginning of the frame is 25 bits and 27 groups following the startgroup is 45 bits, and then, a dcc with a size of 1 bit is inserted intoa location right behind each of the groups. On the other hand, the framesync having a size of 20 bits is placed at a location in front of thestart group to produce the recording frame having a size of 1,288 bits(1,240 bits of the original frame+20 bits of the frame sync+28 bits ofdcc). The 1,288 bits of the recording frame are subjected to the RLL (1,7) PP modulation process to generate 1,932 channel bits of a modulatedrecording frame. In the RLL (1, 7) PP modulation process, every 2 databits of the recording frame are converted into 3 channel bits of themodulated recording frame.

Such recording frames constitute a data structure to be recorded onto atrack in the RW zone on the disc.

In the case of a DVR disc, the recording density is thought to be about0.08 μm per channel bit output by the RLL (1, 7) PP modulation process.

Since the BIS is a code having an extremely excellent an errorcorrection power in comparison with the LDC, almost all errors arecorrected. That is to say, the BIS is a code using a code distance of 33for a code length of 62.

Symbols serving as error pointers provided by erroneous BIS can be usedas follows.

In a decoding process using ECC, BIS are decoded first. Assume that twoerrors are detected in consecutive BIS (or the sync frame) in the dataframe structure shown in FIG. 4. In this case, the 38 bytes datasandwiched by the consecutive BIS is regarded as a burst error. Errorpointers are added to the 38 bytes data. Then, a pointer erasurecorrection process based on LDC is carried out by using these errorpointers.

In this way, the error correction power is increased over the power ofthe error correction using only LDC.

BIS include, among other data, address information. These addresses canbe used for a case in which address information is not included in awobbling groove as is the case with a ROM-type disc.

FIG. 6 is an explanatory diagram showing the structure of a clusterincluding data frames.

Each row shown in the figure corresponds to a data frame having a sizeof 155 bytes as described above. As explained earlier, each data frameis modulated to produce a recording frame having a size of 1,932 channelbits. 496 rows or 496 frames constitute an ECC block. A run-in frame anda run-out frame are added to the ECC block respectively before and afterthe 496 frames to form a RUB (Recording Unit Block) having 498 frames.The RUB is the cluster cited above. The run-in and run-out frames areeach used as a linking frame.

In addition, as described above, 16 addresses are each added as anaddress unit number. The cluster's LDC portion excluding the run-in andrun-out frames includes 496 frames, which are divided into 16 groupseach having 31 frames, namely, frame 0 to frame 30. The 16 addresses,namely, having unit numbers 0 to 15, are assigned to the 16 groups on aone-to-one basis.

4. ADIP Addresses

The following description explains ADIP addresses recorded as a groovewobbling shape in the RW zone.

FIG. 7 is an explanatory diagram showing use of an MSK (Minimum ShiftKeying) technique, which is one of FSK modulation methods, as atechnique of modulating ADIP addresses that the grove is wobbled.

As a data detection unit, two wobble segments are taken. It is to benoted that a wobble segment is a wobble period defined as the reciprocalof a carrier frequency.

Data such as an address is subjected to a differential encoding processprior to a recording process in a unit of one wobble (or window lengthunits shown in FIG. 7A). To put it in detail, the differential encodingprocess encodes input data having a value of “one” into prerecorded dataalso having a value of “one” during a wobble period between rising andfalling edges prior to the recording process as shown in FIG. 7B.

Then, the prerecorded data is subjected to the MSK modulation process togenerate an MSK stream shown in FIG. 7C. To put it in detail,prerecorded data having a value of “zero” is modulated into a carriercos ωt or −cos ωt. On the other hand, prerecorded data having a value of“one” is modulated into a carrier cos 1.5 ωt or −cos 1.5 ωt with afrequency 1.5 times the frequency of the carrier obtained as a result ofthe MSK modulation process carried out on prerecorded data having avalue of “zero”.

Assume that one channel bit of recorded or reproduced phase change datacorresponds to one channel. In this case, the period of the carrier iscapable of accommodating 69 channels as shown in FIG. 7C.

By the way, 1 data bit of an ADIP completing an MSK modulation processoccupies 56 wobble periods while a wobble period is capable ofaccommodating 69 channel bits obtained as a result of the RLL (1, 7) PPmodulation process applied to user data as is explained earlier byreferring to FIG. 3A.

Thus, the recording density of ADIP data bits is 1/2,576 times therecording density of user data obtained as a result of the RLL (1, 7) PPmodulation process.

In the case of this embodiment, for one RUB (Recording Unit Block) orone recording cluster, which is used as a recording unit of the userdata described above, three addresses can be included as ADIP addresses.

FIG. 8 is an explanatory diagram showing a state of inclusion of the 3address blocks including the 3 addresses in 1 RUB. As shown in FIG. 6, aRUB (or a recording cluster) includes 496 frames, which form an ECCblock, and 2 frames, namely, the run-in and run-out frames. Thus, a RUBincludes a total of 498 frames, serving as a recording unit.

As shown in FIG. 8A, in a segment corresponding to 1 RUB, 3 ADIP addressblocks are included. An address block consists of 83 bits.

FIG. 8B is a diagram showing the configuration of an address blocks. Theaddress block consisting of 83 bits includes a sync part (or asynchronization signal part) having a size of 8 bits and a data parthaving a size of 75 bits.

The sync part having a size of 8 bits includes four units eachconsisting of 1 monotone bit and 1 sync bit.

On the other hand, the data part having a size of 75 bits includes 15ADIP block units each consisting of 1 monotone bit and 4 ADIP bits.

One monotone bit, one sync bit, and one ADIP bit each occupies 56 wobbleperiods. At the head of the bit, an MSK mark exists to serve as abit-sync.

Wobble periods each defined as the reciprocal of the carrier frequencyare created for the monotone bit, following the MSK mark of the monotonebit. Details of the sync bit and the ADIP bit will be described later.Anyway, wobble periods of an MSK modulation waveform are created for thesync bit, following the MSK mark of the sync bit. By the same token,wobble periods of an MSK modulation waveform are created for the ADIPbit, following the MSK mark of the ADIP bit.

FIG. 9 is an explanatory diagram showing the configuration of the syncpart.

As is obvious from FIGS. 9A and 9B, the sync part having a size of 8bits includes four sync blocks, namely, sync blocks “0”, “1”, “2”, and“3”, each consisting of two bits, namely, a monotone bit and a sync bit.

To be more specific,

sync block “0” constitutes of a monotone bit and a sync “0” bit,

sync block “1” constitutes of a monotone bit and a sync “1” bit,

sync block “2” constitutes of a monotone bit and a sync “2” bit and

sync block “3” constitutes of a monotone bit and a sync “3” bit.

As described above, a monotone bit in each sync block is a waveform overa series of wobble periods of a carrier having a single frequency. Toput it in detail, a monotone bit includes 56 wobble periods as shown inFIG. 10A. At the head of the 56 wobble periods, an MSK mark bs exists toserve as a bit-sync bs. The remaining wobble periods each defined as thereciprocal of the single carrier frequency are created for the monotonebit, following the MSK mark of the monotone bit. It is to be noted thatthe MSK mark pattern is shown beneath a wobble period in each of FIGS.10A to 10E.

As described above, there are 4 kinds of sync bit, namely, the sync “0”bit, the sync “1” bit, the sync “2” bit, and the sync “3” bit. The sync“0” bit, the sync “1” bit, the sync “2” bit, and the sync “3” bit areconverted into wobble waveform patterns shown in FIGS. 10B, 10C, 10D,and 10E respectively.

In the case of the wobble waveform pattern for the sync “0” bit shown inFIG. 10B, an MSK mark exists at the beginning to serve as a bit-sync bs.The head MSK mark is followed by a second MSK mark separated from thehead MSK by 16 wobble periods. Thereafter, successive MSK marks followthe second MSK mark at intervals of 10 wobble periods.

In the case of the wobble waveform pattern for the sync “n”, the secondMSK mark exists at a position lagging behind the second MSK mark of thesync “n−1” bit by 2 wobble periods and, thereafter, successive marksfollow at positions lagging behind the counterpart successive MSK marksof the sync “n−1” bit by two wobble periods, where n=1 to 3.

To be more specific, in the case of the wobble waveform pattern for thesync “1” bit shown in FIG. 10C, an MSK mark exists at the beginning toserve as a bit-sync bs. The head MSK mark bs is followed by a second MSKmark separated from the head MSK by 18 wobble periods. Thereafter,successive MSK marks follow the second MSK mark at intervals of 10wobble periods.

By the same token, in the case of the wobble waveform pattern for thesync “2” bit shown in FIG. 10D, an MSK mark exists at the beginning toserve as a bit-sync. The head MSK mark is followed by a second MSK markseparated from the head MSK bs by 20 wobble periods. Thereafter,successive MSK marks follow the second MSK mark at intervals of 10wobble periods.

In the same way, in the case of the wobble waveform pattern for the sync“3” bit shown in FIG. 10E, an MSK mark exists at the beginning to serveas a bit-sync bs. The head MSK mark is followed by a second MSK markseparated from the head MSK by 22 wobble periods. Thereafter, successiveMSK marks follow the second MSK mark at intervals of 10 wobble periods.

Each sync pattern includes a pattern unique to a monotone bit and a syncbit and ADIP bits to be described later. As described above, there arefour different sync-bit patterns. By including each of these differentsync-bit pattern in every sync block of a sync part, the disc driveapparatus is capable of detecting and recognizing any of these sync-bitpatterns included in the sync blocks and as well as establishingsynchronization.

By referring to FIG. 11, the following description explains the datapart of an address block. As shown in FIGS. 11A and 11B, the data partincludes 15 ADIP blocks, namely, ADIP blocks “0” to “14”, which eachconsist of 5 bits.

Each of the 5 bit ADIP blocks includes one monotone bit and 4 ADIP bits.

Much like the sync block, 1 monotone bit of the ADIP block occupies 56wobble periods. At the head of the bit, an MSK mark exists to serve as abit-sync bs. Wobble periods each defined as the reciprocal of thecarrier frequency are created for the monotone bit, following the MSKmark of the monotone bit. A waveform representing the MSK mark and thefollowing wobble periods is shown in FIG. 12A.

Since an ADIP block includes 4 ADIP bits, the 15 ADIP blocks canaccommodate 60 ADIP bits of address information.

Wobble waveform patterns of “1” and “0” ADIP bits are shown in FIGS. 12Band 12C respectively.

As shown in FIG. 12B, in the case of the wobble waveform pattern of the“1” ADIP bit, an MSK mark exists at the beginning to serve as a bit-syncbs. The head MSK mark is followed by a second MSK mark separated fromthe head MSK by 12 wobble periods.

As shown in FIG. 12C, in the case of the wobble waveform pattern of the“0” ADIP bit, an MSK mark also exists at the beginning to serve as abit-sync bs. However, the head MSK mark is followed by a second MSK markseparated from the head MSK by 14 wobble periods.

As described above, MSK-modulated data is recorded along a wobblinggroove. FIG. 13 is a diagram showing an address format of the ADIPinformation recorded as described above.

FIG. 13 also shows a method of correcting errors in ADIP addressinformation.

The actual ADIP address information has a size of 36 bits, to which 24parity bits are added.

The ADIP address information with a size of 36 bits includes a 3 layernumber bits (namely, layer number bit 0 to layer number bit 2), whichare used for multi-layer recording purposes, 19 RUB (Recording UnitBlock) bits (namely, RUB bit 0 to RUB bit 18), 2 address number bits(namely, address number bit 0 to address number bit 1), and 12 auxiliarydata bits. The 2 address number bits are used for identifying 3 addressblocks for 1 RUB. The auxiliary data includes the ID of the disccontaining stored recording conditions such as the power of arecording/reproduction laser.

The ECC unit of address data is the unit constituting a total of 60 bits(36 bits+24 parity bits) described above. As shown in the figure, the 60bits are 15 nibbles, namely, nibble 0 to nibble 14, where a nibbleconstitutes of 4 bits.

As an error correction technique, the nibble-based Reed-Solomon encodingRS (15, 9, 7) technique is adopted. In accordance with this technique, 4bits are treated as a symbol. Notation (15, 9, 7) means a code length of15 nibbles, a data size of 9 nibbles, and a code distance of 6 nibbles.

5. Prerecorded Information (Shipping-Time Information)

FIGS. 14A to 14K are explanatory diagrams showing a method of modulatingprerecorded information (or shipping-time information) for forming awobbling groove in the prerecorded data zone.

As a modulation technique, a bi-phase modulation technique such as an FMcode modulation technique is adopted.

FIG. 14A shows values of a data bit and FIG. 14B shows a channel clocksignal. FIG. 14C shows FM codes and FIG. 14D shows wobble waveforms.

One data bit is 2 ch (2 channel clock). The FM code for a data bit of“1” is represented by a frequency ½ times the frequency of the channelblock.

The FM code for a data bit of “0” is represented by a frequency ½ timesthe frequency of the FM code for a data bit of “1”.

A wobble waveform recorded as a groove wobbling shape can be arectangular waveform directly representing the FM code. As analternative, a waveform recorded as a groove wobbling shape can be asinusoidal waveform shown in FIG. 14D.

It is to be noted that the polarities of the patterns of the FM code andthe wobble waveform, which are shown in FIGS. 14C and 14D respectively,can be inverted to result in patterns shown in FIGS. 14E and 14Frespectively.

Let the rules of the FM code modulation described above be applied to adata bit stream of “10110010” shown in FIG. 14G. In this case, themodulation produces an FM code waveform and a wobble waveform(sinusoidal waveform), which are shown in FIGS. 14H and 14Irespectively.

It is to be noted that the modulation may also produce an FM codewaveform and a sinusoidal wobble waveform, which are shown in FIGS. 14Jand 14K respectively, by inverting the polarities of the patterns of theFM code and the wobble waveform in FIGS. 14H and 14I respectively.

The structure of an ECC block of shipping-time information is describedby referring to FIG. 15. The ECC data block of shipping-time informationphysically comprises roughly two sectors. From a content point of view,the data block includes a sub-block of actual shipping-time information(or prerecorded data) and a sub-block of control data related to theactual shipping time information (prerecorded control data).

As shown in FIG. 15, the sub-block of prerecorded data comprises twounits each occupying a sector having a size of 2 K bytes. The two unitsform the sub-block having a size of 4 K byte (=2,048 bytes/sector×2sectors).

A 4 bytes EDC (Error Detection Code) is added to each sector to form adata-frame unit. 2 data-frame units form a data frame having a size of2,052 (=2,048+4) bytes/data-frame unit×2 data-frame units. The dataframe is further scrambled to produce a scrambled data frame.

Then, the scrambled data frame is subjected to a Reed-Solomon encodingprocess to generate a data block of 216 rows and 19 columns. 32 rows ofparity are further added to the data block to generate an LDC (LongDistance Code) sub-block of (216+32) rows and 19 columns. The LDCsub-block is an RS (248, 216, 33)×19 block.

Then, an LDC cluster of 248 rows×19 columns (19 bytes) is formed fromthe LDC sub-block.

FIGS. 16A and 16B are diagrams showing a process to encode the sub-blockof prerecorded data into the LDC sub-block.

The 4 K bytes prerecorded data shown in FIG. 16A is subjected to an ECCencoding process to produce the LDC sub-block shown in FIG. 16B. To putit in detail, a 4-byte EDC (Error Detection Code) is added to each2,048-byte sector of the prerecorded data. The two sectors of theprerecorded data are then encoded into an LDC sub-block. As mentionedabove, the LDC sub-block is an RS (248, 216, 33)×19 block. An RS (248,216, 33)×19 block is a block, which is composed of the RS (Reed-Solomon)code with a code length of 248 nibbles, a data size of 216 nibbles and acode distance of 33 nibbles and has a block size of 19 code words.

On the other hand, the sub-block of prerecorded control data has a sizeof 48 bytes (=24 bytes/unit×2 units) as shown in FIG. 15. Address unitnumbers having a size of 72 bytes (9 bytes/address×8 addresses) areadded to the sub-block of prerecorded control data to generate anencoding unit having a size of 120 bytes (=48 bytes+72 bytes).

The 120 bytes are subjected to the Reed-Solomon encoding process toproduce an access block of 30 rows×4 columns.

Then, 32 rows of parity are added to form a BIS (Burst-Indicating Subcode) sub-block. The BIS sub-block is an RS (62, 30, 33)×4 block. Then,a BIS cluster of 248 rows×1 column (1 byte) is formed from the BISsub-block.

FIGS. 16C and 16D are diagrams showing a process to encode theprerecorded control data and the address unit number, which have a totalsize of 120 bytes, into the BIS sub-block.

That is to say, the 120 bytes of data shown in FIG. 16C are subjected toan ECC encoding process to generate the BIS sub-block shown in FIG. 16D.As mentioned above, the BIS sub-block is an RS (62, 30, 33)×4 block. AnRS (62, 30, 33)×4 block is a block, which is composed of the RS(Reed-Solomon) code with a code length of 62 nibbles, a data size of 30nibbles and a code distance of 33 nibbles and has a block size of fourcode words.

As shown in FIG. 15, the LDC and BIS clusters, each comprises 248 rowseach constituting a data frame. A data frame of the LDC clustercomprises 19 bytes while a data frame of the BIS cluster comprises 1byte.

Thus, a combined data frame comprises 20 bytes (=19 bytes+1 byte). Asshown in the figure, the BIS having a size of 1 byte is placed at thehead of the combined data frame. The BS is followed by the LDC having asize of 19 bytes. 248 rows or 248 data frames each having a size of 20bytes (=160 bits) constitute an ECC block.

Each of the data frames is subjected to a bi-phase modulation process,in which a frame sync is added to generate a recording frame. To put itin detail, the frame sync having a size of 8 bits is inserted into thehead of 20-byte (160-bit) data obtained as a result of the bi-phasemodulation process to produce a structure consisting of 336 channel bitsas a final result of the bi-phase modulation process.

It is to be noted that, since there is no DC component in the case ofthe bi-phase modulation, it is not necessary to add dcc bits to the dataframe.

Such recording frames constitute a data structure to be recorded onto atrack as a wobbling groove in the PB zone on the disc.

To put it in detail, the prerecorded information used as shipping-timeinformation is recorded onto the PB zone, which is an area between acircumference with a radius of 22.3 mm and a circumference with a radiusof 23.1 mm in the case of a disc having a diameter of 12 cm as describedearlier by referring to FIG. 2.

To consider merely a condition requiring that a data block ofshipping-time information shall be recorded in the format describedabove into the PB zone's area not exceeding the circle of acircumference on the disc, the recording density of channel bits can bemade less dense to a value of about 1.72 μm.

That is to say, the recording density of channel bits can be reduced toabout 1/28 times the recording density of user data obtained as a resultof the modulation adopting the RLL (1,7) PP technique. As a result, theS/N ratio of a signal representing the channel bits can be improved.

Since the BIS is a code having an extremely excellent error correctionpower in comparison with the LDC, almost all errors are corrected. Thus,symbols serving as error pointers provided by erroneous BIS can be usedas follows.

In a decoding process using ECC, BIS are decoded first. Assume that twoerrors are detected in consecutive BIS. In this case, the two errors areregarded as a burst error in the 19-byte data sandwiched by theconsecutive BIS. Error pointers each pointing to one of the errors areadded to the 19-byte data. Then, a pointer erasure correction processbased on LDC is carried out by using these error pointers.

In this way, the error correction power is increased over the power ofthe error correction using only LDC.

BIS include, among other data, address information. In a prerecordeddata zone, prerecorded information is stored as a groove wobbling shape.Thus, since the groove wobbling shape does not express addressinformation, the address information included in BIS can be used inmaking an access.

As is obvious from FIG. 15 (or FIGS. 16A to 16D) and FIG. 4 (or FIGS. 5Ato 5D), the ECC format of user data stored as phase change marks usesthe same codes as the ECC format of shipping-time information.

The fact that the ECC formats share the same codes implies that the ECCdecoding process of shipping-time information (or prerecordedinformation) can be carried out by the circuit system for performing theECC decoding process of reproduction of user data stored as phase changemarks, and also means that the hardware configuration of the disc driveapparatus can be made more efficient.

FIG. 17 is an explanatory diagram showing the structure of a clustercomprising data frames.

Each row shown in the figure corresponds to a data frame having a sizeof 20 bytes as described above. As explained earlier, each data frame ismodulated to produce a recording frame having a size of 336 channelbits. 248 rows or 248 frames constitute an ECC block. A run-in frame anda run out frame are added to the ECC block respectively before and afterthe 248 frames to form the aforementioned cluster having 250 frames. Therun-in and run out frames are each used as a linking frame.

In addition, as described above, 8 addresses are each added as anaddress unit number. The cluster's LDC portion excluding the run-in andrun out frames comprises 248 frames, which are divided into eight groupseach having 31 frames, namely, frame 0 to frame 30. The 8 addresses,namely, addresses having unit numbers 0 to 7, are assigned to the eightgroups on a one-to-one basis.

It is to be noted that the prerecorded data's cluster structure shown inFIG. 17 is a typical cluster structure obtained by adding the linkingframes in conformity with the cluster structure of user data. Theprerecorded data's cluster structure conforming to the cluster structureof user data is amenable to the design of the circuit configuration of adecode processing system employed in the disc drive apparatus.

However, it is not always necessary to design the cluster structure ofthe prerecorded data (or the shipping-time information) in conformitywith the cluster structure of user data if the unconformity does notcause a problem.

That is to say, since the shipping-time information is reproduction-onlyinformation, which is never rewritten, the linking frames are notrequired. Thus, with the linking frames eliminated, a cluster comprisingonly 248 frames as shown in FIG. 18 is also conceivable.

By referring to FIGS. 19 to 26, the following description explainsdata-series conversion processing such as an interleaving processcarried out on LDC and BIS sub-blocks.

FIGS. 19 to 21 are explanatory diagrams used for describing conversionprocessing carried out on an LDC sub-block. On the other hand, FIGS. 22Ato 25 are explanatory diagrams used for describing conversion processingcarried out on a BIS sub-block. FIG. 26 is an explanatory diagram usedfor describing conversion processing, which is carried out when data ofLDC and BIS sub-blocks is recorded onto a disc.

FIG. 19 is an explanatory diagram used for describing a process toconvert prerecorded data C(g, h) used as actual shipping-timeinformation into data D(i, j) recorded on a memory, where the subscriptg in the range 0≦g<2 denotes a unit number and the subscript h in therange 0≦h<2,052 denotes prerecorded data number. The conversionprocessing is carried out on the basis of conversion equations using theunit number g and the prerecorded data number h as follows:

i=(g×2,052+h) % 216

j=(g×2,052+h)/216

where symbol “/” denotes a division operator for finding a quotient jand symbol “%” denotes a division operator for finding a divisionremainder i.

C(g, 2,048) to C(g, 2,051) are EDC (Error Detection Codes) for C(g, 0)to C(g, 2,047).

The (2,052×2)-byte prerecorded data including EDC as shown in FIG. 15 isconverted into data D (i, j) loaded into a memory as shown in FIG. 19where 0≦i≦215 and 0≦j≦18. Notations “0, 0” to “1, 2051” shown in FIG. 19denote the prerecorded data C(g, h).

FIG. 20 is a diagram showing codes of the prerecorded data's memory dataD(i, j) loaded into a memory as described above where the subscript i isa code number and the subscript j is a byte number.

A hatched portion corresponding to the subscript i's values in the range216≦i≦247 represents 32 added rows of parity.

FIG. 21 is a diagram showing positions b(s, t, u) obtained as a resultof a conversion process carried out on the memory data D(i, j) like theone shown in FIG. 20 where the subscript s is an AUN (Address UnitNumber), the subscript t is a frame number and the subscript u is a bytenumber.

The conversion process is carried out on the basis of conversionequations using the address unit number s, the frame number t and thebyte number u as follows:

i=(s×31+t)

j=(s×31+t+u−1) % 19

where 0≦s<8, 0≦t<31 and 1≦u<20.

FIGS. 22 to 25 are explanatory diagrams used for describing conversionprocessing carried out on prerecorded control data used as addition &control information for the shipping-time information.

FIG. 22 is an explanatory diagram showing information included in a BISsub-block.

As described earlier, the BIS information comprises address informationand prerecorded control data.

The address information in the BIS information is shown in FIG. 22A. Asshown in the figure, an address in one ECC block comprises eight addressfields, namely, address field #0 to address field #7. Each of theaddress fields comprises 9 bytes. For example, address field #0comprises 9 bytes, namely, byte 0-0 to byte 0-8.

The 4 MSB (Most Significant Bytes) of each address field are used forstoring an address value showing an ECC block address called an AUN(Address Unit Number).

The 3 LSB (Least Significant Bits) of the 5th byte in each address fieldis used for storing the number of the address field.

The descendant 4 LSB (Least Significant Bytes) of each address field areused for storing parity bits for the address field.

On the other hand, the prerecorded control data in the BIS informationis shown in FIG. 22B. As shown in the figure, the prerecorded controldata in one ECC block comprises 2 units, namely, unit #0 and unit #1,which each consist of 24 bytes. For example, unit #0 is composed of 24bytes, namely, byte 0-0 to byte 0-23.

This prerecorded control data is reserved for future use.

FIG. 23 is an explanatory diagram used for describing processing toconvert the BIS sub-block's address information I(s, v) and prerecordedcontrol data U(g, h) into memory data B(i, j).

In the address information I(s, v), the subscript s is an AUN (AddressUnit Number) in the range #0 to #7 and the subscript v is an addressnumber, that is, a byte number in the range 0 to 8.

In the prerecorded control data U(g, h), on the other hand, thesubscript g is a unit number in the range #0 to #1 and the subscript his a data number, that is, a byte number in the range 0 to 23.

The conversion processing for the address information is carried out onthe basis of conversion equations using the address unit number s andthe byte number v as follows:

i = ((s × 31 + v)%31) × 2 + ((s × 31 + v)/124)   = (v %31) × 2 + (s/4)j = (s × 31 + v)%4

where 0≦s<8 and 0≦v<9. The address information is loaded into a memory,by being interleaved in a range of 18 rows, that is, in the range0≦i≦17.

As for the prerecorded control data, the conversion processing iscarried out on the basis of conversion equations using the unit number gand the byte number h as follows:

i=(g×24+h) % 12+18

j=(g×24+h)/12

where 0≦g<2 and 0≦h<24. The prerecorded control data is loaded into amemory in a range of 12 rows, that is, in the range 18≦i≦29.

FIG. 24 is a diagram showing address information and prerecorded controldata, which are loaded in a memory as described above, in terms ofmemory data B(i, j) where the subscripts i and j are a code number and abyte number respectively.

A hatched portion corresponding to the value of subscript i in the range30≦i≦61 represents 32 added rows of parity.

FIG. 25 is a diagram showing processing to convert the memory data B(i,j) like the one shown in FIG. 24 into positions b(s, t, u) on the discwhere the subscripts s, t and u are an AUN (Address Unit Number), aframe number and a byte number respectively.

The conversion processing is carried out on the basis of conversionequations using the address unit number s, the frame number t and thebyte number u set at 0 as follows:

$\begin{matrix}\begin{matrix}{i = {{\left( {\left( {{s \times 31} + t} \right){\% 31}} \right) \times 2} + \left( {\left( {{s \times 31} + t} \right)/124} \right)}} \\{= {{\left( {t\mspace{11mu} {\% 31}} \right) \times 2} + \left( {s/4} \right)}} \\{j = {\left( {{s \times 31} + t} \right){\% 4}}}\end{matrix} & \; \\{{{{where}\mspace{14mu} 0} \leqq s < 8},{{0 \leqq t < {31\mspace{14mu} {and}\mspace{14mu} u}} = 0.}} & \;\end{matrix}$

The data at the positions b(s, t, u) shown in FIG. 21 to representresults of a process to convert an LDC sub-block and the data at thepositions b(s, t, u) shown in FIG. 25 to represent results of a processto convert an BIS sub-block jointly form frames recorded on the disc asshown in FIG. 26.

It is to be noted that the conversion rules of data processing toconvert shipping-time information are also applicable to user data aswell.

By the way, the above description explains the shipping-timeinformation's typical case in which an ECC block is constructed as a 4 Kbytes unit of prerecorded data. However, an ECC block constructed as an8 K bytes unit of prerecorded data is also conceivable.

The structure of an ECC block constructed as an 8 K bytes unit ofprerecorded data is explained by referring to FIG. 27.

In this case, the ECC data block of shipping-time information physicallycomprises roughly four sectors.

Thus, the sub-block of prerecorded data includes four frames eachoccupying a sector having a size of 2 K bytes. The four frames form thesub-block having a size of 8 K bytes (=2,048 bytes/sector×4 sectors).

A 4-byte EDC (Error Detection Code) is added to each sector to form adata-frame unit. 4 data-frame units form a data frame having a size of2,052 (=2,048+4) bytes/data-frame unit×4 data-frame units. The dataframe is further scrambled to produce a scrambled data frame.

Then, the scrambled data frame is subjected to a Reed-Solomon encodingprocess to generate a data block of 216 rows and 38 columns. 32 rows ofparity are further added to the data block to generate an LDC (LongDistance Code) sub-block of (216+32) rows and 38 columns. The LDCsub-block is an RS (248, 216, 33)×38 block, which is composed of the RS(Reed-Solomon) code with a code length of 248 nibbles, a data size of216 nibbles and a code distance of 33 nibbles and has a block size of 38code words.

Then, an LDC cluster of 496 rows×19 columns (19 bytes) is formed fromthe LDC sub-block.

On the other hand, the sub-block of prerecorded control data has a sizeof 96 bytes (=24 bytes/unit×4 units). Address unit numbers having a sizeof 144 bytes (9 bytes/address×16 addresses) are added to the sub-blockof prerecorded control data to generate an encoding unit having a sizeof 240 bytes (=96 bytes+144 bytes).

The 240 bytes are subjected to the Reed-Solomon encoding process toproduce an access block of 30 rows×8 columns.

Then, 32 rows of parity are added to form a BIS (Burst-Indicating Subcode) sub-block. The code words is 8. The BIS sub-block is an RS (62,30, 33)×8 block which is composed of the RS (Reed-Solomon) code with acode length of 62 nibbles, a data size of 30 nibbles and a code distanceof 33 nibbles and has a block size of eight code words. Then, a BIScluster of 496 rows×1 column (1 byte) is formed from the BIS sub-block.

The LDC and BIS clusters each includes 498 rows each constituting a dataframe. A data frame of the LDC cluster comprises 19 bytes while a dataframe of the BIS cluster comprises 1 byte.

Thus, a combined data frame comprises 20 bytes (−19 bytes+1 byte). Asshown in the figure, the BIS having a size of 1 byte is placed at thehead of the combined data frame. The BIS is followed by the LDC having asize of 19 bytes. 496 rows or 496 data frames each having a size of 20bytes constitute an ECC block.

Each of the data frames is subjected to a bi-phase modulation process,in which a frame sync is added to generate a recording frame. To put itin detail, the frame sync having a size of 8 bits is inserted into thehead of 20-byte (160-bit) data obtained as a result of the bi-phasemodulation process to produce a structure consisting of 336 channel bitsas a final result of the bi-phase modulation process.

It is to be noted that, since there is no DC component in the case ofthe bi-phase modulation, it is not necessary to add dcc bits to the dataframe.

Such recording frames constitute a data structure to be recorded as awobbling groove onto a track in the PB zone on the disc.

To put it in detail, the prerecorded information used as shipping-timeinformation is recorded onto the PB zone, which is an area between acircumference with a radius of 22.3 mm and a circumference with a radiusof 23.1 mm in the case of a disc having a diameter of 12 cm as describedearlier by referring to FIG. 2.

To consider merely a condition requiring that a data block ofshipping-time information shall be recorded in the format describedabove into the PB zone's area not exceeding the circle of acircumference on the disc, the recording density of channel bits can bemade less densely to a value of about 0.86 μm. That is to say, therecording density of channel bits can be reduced to about 1/14 times therecording density of user data obtained as a result of the modulationadopting the RLL (1,7) PP technique. As a result, the S/N ratio of asignal representing the channel bits can be improved.

In addition, also in this case, the ECC format of user data stored asphase change marks uses the same codes as the ECC format ofshipping-time information.

FIG. 28 is a diagram showing the structure of a cluster comprising dataframes.

Each row shown in the figure corresponds to a data frame having a sizeof 20 bytes as described above. As explained earlier, each data frame ismodulated to produce a recording frame having a size of 336 channelbits. 496 rows or 496 frames constitute an ECC block. A run-in frame anda run out frame are added to the ECC block respectively before and afterthe 496 frames to form the aforementioned cluster having 498 frames. Therun-in and run out frames are each used as a linking frame.

In addition, as described above, 16 addresses are each added as anaddress unit number. The cluster's LDC portion excluding the run-in andrun out frames comprises 496 frames, which are divided into 16 groupseach having 31 frames, namely, frame 0 to frame 30. The 16 addresses,namely, addresses having unit numbers 0 to 15, are assigned to the 16groups on a one-to-one basis.

It is to be noted that the prerecorded data's cluster structure shown inFIG. 28 is a typical cluster structure obtained by adding the linkingframes in conformity with the cluster structure of user data. Theprerecorded data's cluster structure conforming to the cluster structureof user data is amenable to the design of the circuit configuration of adecode processing system employed in the disc drive apparatus.

However, it is not always necessary to design the cluster structure ofthe prerecorded data (or the shipping-time information) in conformitywith the cluster structure of user data if the unconformity does notcause a problem.

That is to say, since the shipping-time information is reproduction-onlyinformation, which is never rewritten, the linking frames are notrequired. Thus, with the linking frames eliminated, a cluster comprisingonly 496 frames as shown in FIG. 29 is also conceivable.

FIGS. 30 and 31 are explanatory diagrams showing frame synchronizationsof the 4 K bytes or 8 K bytes ECC block of shipping time information.

As shown in FIG. 30, there are seven types of frame synchronization FS,namely, FS0 to FS6. Each of the frame synchronizations FS0 to FS6 is anout-of-rule pattern of the FM-code modulation. The pattern consists of16 channel bits. Eight of the 16 channel bits are “11001001” serving asa sync body. The remaining 8 channel bits form a sync ID identifying theframe sync.

Expressed in terms of data bits, for example, the sync ID of the framesync FS0 is 3 bits “000” and 1 parity bit, which is 0 in this case.These 3 data bits and the parity bit are subjected to an FM codemodulation process to result in the 8 channel bits “10101010”.

The 8 channel bits for each of the other frame synchronizations FS1 toFS7 are obtained in the same way as the frame sync FS0. That is to say,the 3 data bits “000” and 1 parity bit of each frame sync are subjectedto an FM code modulation process to result in 8 channel bits for theframe sync.

Thus, the code distance of the bit data becomes 2 nibbles or longer sothat a 1-bit error will not cause a sync ID to be interpreted as anothersync ID.

In an operation to record a frame sync FS, the frame sync FS issubjected to an NRZI conversion before being recorded.

FIG. 31 is a diagram showing mapping of frame synchronizations.

As described above, in the case of an ECC block built as a 4 K bytesunit, one ECC block including 248 frames is divided into eight groupseach having 31 frames. In the case of an ECC block built as a 8 K bytesunit, on the other hand, one ECC block including 496 frames is dividedinto 16 groups each having 31 frames. In either case, an ECC block isdivided into groups each having 31 frames.

Frame numbers 0 to 30 are assigned to respectively the 31 frames of eachgroup. For frame number 0, a FS0 is used as a special frame sync notused for other frame numbers. Thus, the frame sync FS0 allows thebeginning of an address frame to be detected and, hence, addresssynchronization to be established.

The frame synchronizations FS1 to FS6 are assigned to frame numbers 1 to30 as shown in FIG. 31. This assignment of the frame synchronizationsFS1 to FS6 allows the beginning of an address frame to be detected evenif the frame sync FS0 is not detected.

6. Disc Drive Apparatus

The following description explains a disc drive apparatus capable ofrecording and reproducing data onto and from the disc described above.

FIG. 32 is a block diagram showing the configuration of the disc driveapparatus. A disc 100 shown in FIG. 32 is the disc implemented by theembodiment described above.

The disc 100 is mounted on a turntable not shown in the figure. Inrecording and reproduction operations, the disc 100 is driven intorotation by a spindle motor 2 at a constant linear velocity (CLV).

Then, an optical pickup 1 reads out ADIP information embedded in the RWzone of the disc 100 as a wobbling shape of a groove track. In addition,the optical pickup 1 also reads out prerecorded information embedded inthe PB zone of the disc 100 as a wobbling shape of a groove track.

In a recording operation, the optical pickup 1 records user data intothe RW zone as phase change marks. In a reproduction operation, on theother hand, the optical pickup 1 reads out the recording phase changemarks.

The optical pickup 1 includes a laser diode, a photodetector, anobjective lens and an optical system, which is not shown in the figure.The laser diode serves as a laser-beam source. The photodetector detectsa reflected beam. The objective lens serves as an output end of a laserbeam. The optical system makes the laser beam radiate the recordingsurface of the disc 100 by way of the objective lens and leads thereflected beam to the photodetector.

The laser diode outputs the so-called blue-color laser having awavelength of 405 nm. The optical system has an NA of 0.85.

The objective lens is held in the optical pickup 1 by a 2-shaftmechanism in such a way that the lens can be moved in tracking and focusdirections. The entire optical pickup 1 itself can be moved by a threadmechanism 3 in the radial direction of the disc 100. The laser diodeemployed in the optical pickup 1 is driven by a drive signal, that is,by a drive current, output by a laser driver 13 to generate a laser.

Information conveyed by a beam reflected from the disc 100 is detectedby the photodetector, which converts the information into an electricalsignal and outputs the signal to a matrix circuit 4. The matrix circuit4 includes a current-to-voltage conversion circuit and amatrix-processing/amplification circuit. The current-to-voltageconversion circuit converts currents output by a plurality of alight-receiving devices each serving as a photodetection means into avoltage. The matrix-processing/amplification circuit carries out matrixprocessing on the voltage received from the current-to-voltageconversion circuit to generate required signals such as a high-frequencysignal (or a reproduced-data signal), a focus error signal and atracking error signal. The high-frequency signal represents reproduceddata. The focus error signal and the tracking error signal are used forexecution of servo control. In addition, thematrix-processing/amplification circuit also generates a signalrepresenting a wobbling shape of the groove, that is, a push-pull signalobtained as a result of detecting the wobbling shape of the groove.

The matrix circuit 4 outputs the reproduced-data signal to areader/writer circuit 5, the focus error signal as well as the trackingerror signal to a servo circuit 11 and the push-pull signal to a wobblecircuit 8.

The reader/writer circuit 5 carries out processes on the reproduced-datasignal to reproduce data read out as phase change marks and outputs thedata to a modulation/demodulation circuit 6. The processes includebinary conversion processing and reproduction clock generationprocessing based on a PLL technique.

The modulation/demodulation circuit 6 includes a functional memberserving as a decoder in a reproduction operation and a functional memberserving as an encoder in a recording operation. In a reproductionoperation, the modulation/demodulation circuit 6 carries out a processto demodulate run-length limited codes on the basis of a reproductionclock signal as a decoding process.

An ECC encoder/decoder 7 carries out an ECC encoding process to adderror correction codes to data to be recorded in a recording operation.In a reproduction operation, on the other hand, the ECC encoder/decoder7 carries out an ECC decoding process to correct errors of reproduceddata. To put it in detail, in a reproduction operation, data demodulatedby the modulation/demodulation circuit 6 is stored in an internalmemory. The data stored in the internal memory is then subjected toprocesses such as error detection/correction processing andde-interleave processing to generate reproduced data.

The reproduced data completing the ECC decoding process carried out bythe ECC encoder/decoder 7 is finally read out to be transferred to an AV(Audio-Visual) system 20 in accordance with a command issued by a systemcontroller 10.

The push-pull signal output by the matrix circuit 4 as a signalrepresenting the wobbling shape of the groove is processed by the wobblecircuit 8. To be more specific, in the wobble circuit 8, the push-pullsignal conveying ADIP information is subjected to an MSK demodulationprocess to generate a data stream composing an ADIP address as a resultof demodulation. The data stream is supplied to an address decoder 9.

The address decoder 9 decodes the data stream received thereby toproduce an address value, and supplies the address value to the systemcontroller 10.

The wobble circuit 8 also carries out a clock generation process basedon a PLL technique on the push-pull signal representing the wobblingshape of the groove to generate a clock signal. For example, thegenerated clock signal is an encoding clock signal supplied to a varietyof components to be used in a recording operation.

The push-pull signal output by the matrix circuit 4 to the wobblecircuit 8 as a signal representing the wobbling shape of the groove is apush-pull signal conveying prerecorded information read out from the PBzone. In the wobble circuit 8, such a push-pull signal is subjected to aband-pass filtering process and an FM-code demodulation process beforebeing supplied to the reader/writer circuit 5 as an FM code stream. Inthe reader/writer circuit 5, the FM code stream is subjected to awaveform reshaping process before being supplied to the ECCencoder/decoder 7, which carries out ECC decoding and de-interleavingprocesses to extract prerecorded information (that is, shipping-timeinformation). The extracted shipping-time information is finallysupplied to the system controller 10.

The system controller 10 carries out processing such as various settingand copy-right protection based on read-out prerecorded information.

The system controller 10 also outputs a control signal CT to the wobblecircuit 8. The control signal CT drives the wobble circuit 8 to switchprocessing from a process to demodulate ADIP information to a process todemodulate shipping-time information or vice versa.

FIG. 33 is a block diagram showing a typical configuration of the wobblecircuit 8.

The push-pull signal PP received from the matrix circuit 4 is passed onto a PLL unit 64 by way of a band-pass filter 61. Typically, the PLLunit 64 carries out a binary conversion process on the push-pull signalPP's carrier component passed on by the band-pass filter 61 prior to aPLL process to generate a clock signal CLK based on the wobbling shapeof the groove. As mentioned above, the push-pull signal PP representsthe wobbling shape of the groove.

As described earlier by referring to FIG. 3, however, the wobblingperiod of the RW zone is 69 T while the wobbling period of the PB zoneis 36 T. That is to say, the wobbling carrier frequency of the RW zoneis different from that of the PB zone.

For this reason, the system controller 10 outputs the control signal CTfor switching the band-pass filter 61 from a pass band for the operationto record or reproduce data onto or from the RW zone to a pass band forthe operation to reproduce data from the BP zone or vice versa.

As a result, the PLL unit 64 generates the clock signal CLK with afrequency corresponding to the wobbling period of 69 T in an operationto record or reproduce data onto or from the RW zone or a frequencycorresponding to the wobbling period of 36 T in an operation toreproduce data from the PB zone.

The push-pull signal PP received from the matrix circuit 4 is alsosupplied to a band-pass filter 62 for extracting a component having acarrier frequency and a component having a frequency 1.5 times thecarrier frequency. These components are supplied to an MSK demodulator65. The MSK demodulator 65 carries out MSK demodulation processing byperforming, among other processes, a process to multiply anMSK-modulated wave by the carrier component and a filtering process. Asresult of the MSK demodulation processing, the MSK demodulator 65outputs modulated data conveying an ADIP address to the address decoder9, which decodes the data to produce the value of the ADIP address. Itis to be noted that the MSK demodulation processing is based on theclock signal CLK having the frequency corresponding to the wobblingperiod of 69 T.

The push-pull signal PP received from the matrix circuit 4 is alsosupplied to a band-pass filter 63 for extracting a bi-phase-modulated(FM-modulated) signal component to be supplied to an FM-code demodulator66, which then demodulates the signal component. A signal obtained as aresult of demodulation is supplied to the reader/writer circuit 5. It isto be noted that the MSK demodulation processing is based on the clocksignal CLK having the frequency corresponding to the wobbling period of36 T.

As described above, the system controller 10 outputs the control signalCT to the wobble circuit 8 having such a configuration, controlling anoperation to switch the clock signal CLK from the frequencycorresponding to the wobbling period of 36 T to the frequencycorresponding to the wobbling period of 69 T or vice versa. That is tosay, in an operation to reproduce data from the PB zone of the disc 100,the FM-code demodulator 66 is driven to carry out a demodulation processfor reproducing shipping-time information. In an operation to reproducedata from the RW zone of the disc 100, on the other hand, the MSKdemodulator 65 is driven to carry out a demodulation process forreproducing an ADIP address.

In a recording operation of the disc drive apparatus shown in FIG. 32,data to be recorded is received from the AV system 20. The data to berecorded is stored in a buffer employed in the ECC encoder/decoder 7.

The ECC encoder/decoder 7 encodes the buffered data to be recorded bycarrying out processing including a process to add error correctioncodes, an interleaving process, and a process to add sub codes. That isto say, the ECC encoder/decoder 7 carries out the encoding processes togenerate an ECC block explained earlier by referring to FIG. 4.

Then, the data completing the ECC encoding processes is subjected to amodulation process adopting an RLL (1, 7) PP technique in themodulation/demodulation circuit 6 before being supplied to thereader/writer circuit 5.

An encoding clock signal to serve as a reference clock signal for theseencoding processes carried out in a recording operation is a clocksignal generated from the push-pull signal representing the wobblingshape of the groove as described above.

In the reader/writer circuit 5, the encoding processes' resultrepresenting data to be recorded is subjected to recording compensationprocessing including a process to finely adjust a recording power to avalue optimum for characteristics of a recording layer on the disc 100,the shape of the spot of the laser beam, the recording linear velocityand the like, and a process to adjust the waveform of laser drivepulses. Then, the data to be recorded is supplied to the laser driver 13as the laser drive pulses.

The laser driver 13 passes on the laser drive pulses to the laser diodeemployed in the optical pickup 1, to drive the diode to generate a laserbeam. As a result, pits (or phase change marks) representing the data tobe recorded are created on the disc 100.

It is to be noted that the laser driver 13 has the so-called APC (AutoPower Control) circuit for controlling a laser output at a constantlevel independent of the ambient temperature and other factors bymonitoring the power of the laser output from an output generated by alaser-power-monitoring detector provided in the optical pickup 1. To putit in detail, the APC circuit adjusts the laser output to a target valueset for a recording or reproduction operation. The target values of thelaser outputs for recording and reproduction operations are set by thesystem controller 10.

The servo circuit 11 generates a variety of servo drive signals such asfocus, tracking, and thread signals based on the focus error signal andthe tracking error signal, which are received from the matrix circuit 4,carrying out servo operations.

To put it in detail, the servo circuit 11 generates a focus drive signaland a tracking drive signal in accordance with the focus error signaland the tracking error signal to drive respectively a focus coil and atracking coil, which are employed in the two-shaft mechanism of theoptical pickup 1. Thus, the optical pickup 1, the matrix circuit 4, theservo circuit 11, and the two-shaft mechanism form a tracking servo loopand a focus servo loop.

In addition, the servo circuit 11 turns off the tracking servo loop andoutputs a jump drive signal to carry out a track jump operation inaccordance with a track jump command received from the system controller10.

Furthermore, the servo circuit 11 generates a thread drive signal basedon a thread error signal obtained as a low-frequency component of thetracking error signal and an access execution control signal receivedfrom the system controller 10. The thread drive signal drives the threadmechanism 3. The thread mechanism 3 is a mechanism including a mainshaft for holding the optical pickup 1, a thread motor, and atransmission gear, which are not shown in the figure. The thread motoris driven in accordance with the thread drive signal to slide theoptical pickup 1 by a required distance.

The spindle servo circuit 12 executes control to rotate the spindlemotor 2 at a CLV.

As information on the present revolution speed of the spindle motor 2,the spindle servo circuit 12 receives a clock signal obtained as aresult of a PLL process carried out on the signal representing thewobbling shape of the groove. The spindle servo circuit 12 compares theinformation on the present revolution speed with information on apredetermined reference CLV to generate a spindle error signal.

In addition, in an operation to reproduce data, a reproduction clocksignal generated by a PLL unit employed in the reader/writer circuit 5(that is, a clock signal serving as a reference signal in a decodingprocess) is used as information on the revolution speed of the spindlemotor 2. By comparing this information on the revolution speed withinformation on the CLV reference speed, a spindle error signal can alsobe generated.

Then, the spindle servo circuit 12 outputs a spindle drive signal inaccordance with the spindle error signal to realize CLV rotation of thespindle motor 2.

In addition, the spindle servo circuit 12 may also generate a spindledrive signal in accordance with the a spindle kick/brake control signalreceived from the system controller 10 in order to implement operationssuch as an activation, a termination, an acceleration, a deceleration,and others of the spindle motor 2.

The variety of operations carried out by the servo system and therecording/reproduction system as described above are controlled by thesystem controller 10 based on a microcomputer.

The system controller 10 performs various kinds of processing inaccordance with commands issued by the AV system 20.

When the AV system 20 issues a write command for storing data to thesystem controller 10, for example, the system controller 10 first of allmoves the optical pickup 1 to an address at which the data is to bewritten. Then, the ECC encoder/decoder 7 and the demodulation circuit 6are driven to carry out the encoding processes on the data received fromthe AV system 20. Examples of the data include video and audio dataconforming to any of a variety of techniques such as the MPEG2technique. Finally, laser drive pulses generated by the reader/writercircuit 5 are supplied to the laser driver 13 in order to record thedata.

In addition, when the AV system 20 issues a read command to the systemcontroller 10, making a request for a transfer of certain data such asMPEG2 video data recorded on the disc 100 to the AV system 20, forexample, a seek operation is first of all controlled with the readcommand's specified address set as a target from which the data is to betransferred. That is to say, a seek command specifying the address isissued to the servo circuit 11 to drive the optical pickup 1 into anoperation of making an access to the target indicated by the addressspecified in the seek command.

Then, operation control is executed to transfer the data in a segmentspecified in the read command to the AV system 20. To put it in detail,the requested data is read out from the disc 100, subjected to processessuch as decoding and buffering carried out by the reader/writer circuit5, the demodulation circuit 6, and the ECC encoder/decoder 7 andsupplied to the AV system 20.

It is to be noted that, in operations to record and reproduce data asphase change marks onto and from the disc 100, the system controller 10controls the recording and reproduction operations by using an ADIPaddress detected by the wobble circuit 8 and the address decoder 9.

In addition, the system controller 10 gives a command to the ECCencoder/decoder 7 to carry out an error correction decoding process onan ECC block having the structure explained earlier by referring to FIG.4.

Furthermore, at a predetermined time such as a time the disc 100 ismounted on the disc drive apparatus, the system controller 10 executescontrol to read out shipping-time information (that is, prerecordedinformation) recorded as a wobbling shape of the groove in the PB zoneon the disc 100.

In this case, first of all, control of a seek operation with the PB zoneset as a target is executed. That is to say, a command is issued to theservo circuit 11 to move the optical pickup 1 in an access to theinnermost circumference of the disc 100.

Then, the optical pickup 1 is driven to move along a reproduction traceto obtain a push-pull signal represented by a reflected beaminformation. Finally, the wobble circuit 8, the reader/writer 5, and theECC encoder/decoder 7 are driven to carry out decoding processes toobtain the reproduced data as prerecorded information.

It is to be noted that the system controller 10 also gives a command tothe ECC encoder/decoder 7 to carry out an error correction decodingprocess on an ECC block having the structure explained earlier byreferring to FIG. 15 or FIG. 27.

In addition, the system controller 10 also carries out processes such asprocessing to set a laser power and copy protection processing on thebasis of the prerecorded information read out from the disc 100 asdescribed above.

It is to be noted that, in an operation to reproduce prerecordedinformation from the PB zone, the system controller 10 controls accessesand reproductions by using address information included in a BIS clusterread out as the prerecorded information.

By the way, in the typical configuration shown in FIG. 32, the AV system20 is connected to the disc drive apparatus 30. It is to be noted,however, that the disc drive apparatus provided by the present inventioncan also be connected to a personal computer or another piece ofequipment.

In addition, the disc drive apparatus provided by the present inventioncan also be connected to no piece of equipment. In this case, the discdrive apparatus is provided with an operation unit and a display unit.The configuration of a member serving as an interface for inputting andoutputting data is also different from that shown in FIG. 32. In thecase of such a standalone disc drive apparatus, recording andreproduction processing is carried out in accordance with operationsperformed by the user, and a terminal unit for inputting and outputtingvarious kinds of data needs to be provided.

It is needless to say that there are many conceivable configurationsother than the typical configuration. For example, implementations ofthe disc drive apparatus provided by the present invention as arecording-only apparatus and a reproduction-only apparatus are alsothinkable.

7. Disc-Manufacturing Method

The following description explains a method of manufacturing the discprovided by the present invention.

Processes of manufacturing the disc are classified into two bigcategories, namely, the so-called mastering process and the so-calledreplication process. The mastering process is a series of process up tocompletion of a metallic master disc called a stamper to be used in thereplication process. On the other hand, the replication process is aprocess using the stamper to mass-produce optical discs as copies of thestamper.

To put it concretely, in the mastering process, a photo resist materialis applied as a light-sensitive film to a ground glass substrate. Then,the so-called cutting process is carried out to create pits and groovesby adoption of a technique of exposure of this light-sensitive film to alaser beam.

In the case of this embodiment, the cutting process is carried out tocreate a groove having a wobbling shape based on prerecorded informationin a portion corresponding to the PB zone on the innermost-circumferenceside of the disc and a groove having a wobbling shape based on ADIPaddresses in a portion corresponding to the RW zone of the disc.

The prerecorded information to be recorded in the PB zone is prepared inprocessing called a pre-mastering process.

As the cutting process is completed, predetermined processing such as adevelopment process is carried out. After the development process,information is transferred to the metallic surface of the glasssubstrate by adoption of an electrocasting technique or the like tocreate a stamper, which will be required later in making discs as copiesof the stamper.

In the replication process following the mastering process, a final discproduct is made by carrying out processing including the steps oftransferring information to a resin substrate by adoption of typicallyan injection method using this stamper, generating a reflective film onthe resin substrate, and fabricating the resin substrate into therequired shape of the disc.

As shown in FIG. 34, a cutting apparatus for carrying out the cuttingprocess includes a prerecorded-information generator 71, an addressgenerator 72, a switching unit 73, a cutting unit 74 and a controller70.

The prerecorded-information generator 71 outputs the prerecordedinformation prepared in the pre-mastering process. The address generator72 generates absolute addresses sequentially.

The cutting unit 74 includes optical-unit components 82, 83, and 84, asubstrate rotator/conveyor 85, a signal processor 81, and a sensor 86.The optical unit consisting the components 82, 83, and 84 radiates alaser beam to the glass substrate 101 covered by a photo-resist materialto do the cutting process. The substrate rotator/conveyor 85 drives theglass substrate 101 into rotation and slides the substrate 101 to conveyit from a place to another. The signal processor 81 converts input datainto data to be recorded and supplies the data to be recorded to theoptical unit. The sensor 86 outputs a signal indicating whether, at thepresent location, the substrate rotator/conveyor 85 places the cuttingposition in the PB or RW zone to the controller 70.

The components 82, 83, and 84 employed in the optical unit are a laserbeam source, a modulator, and a cutting head respectively. The laserbeam source 82 is typically a light source for generating an He—Cd laserbeam. The laser beam radiated by the laser beam source 82 is modulatedby the modulator 83 on the basis of the data to be recorded. The cuttinghead 84 converges a modulated beam output by the modulator 83 andradiates the converged beam to the photo-resist surface of the glasssubstrate 101.

The modulator 83 includes an AOM (Acoustic Optical Modulator) and an AOD(Acoustic Optical Deflector). The AOM turns on and off the beam radiatedby the laser beam source 82. The AOD deflects the beam radiated by thelaser beam source 82 in accordance with a wobbling generation signal.

The substrate rotator/conveyor 85 includes a rotation motor, a speeddetector FG, a slide motor, and a servo controller. The rotation motordrives the glass substrate 101 into rotation. The speed detector FGdetects a revolution speed of the rotation motor. The slide motor slidesthe glass substrate 101 in the radial direction of the glass substrate101. The servo controller adjusts control quantities including therevolution speed of the rotation motor, the revolution speed of theslide motor, and the tracking position of the cutting head 84.

The signal processor 81 carries out processing on prerecordedinformation and address information, which are received through theswitching unit 73. The processing includes a formatting process foradding data such as error correction codes to the prerecordedinformation and the address information to create formatted data, and apredetermined process carried out on the formatted data to create amodulating signal, that is, the signal representing the prerecordedinformation and the address information.

In addition, the signal processor 81 also carries out processing todrive the AOM (Acoustic Optical Modulator) and the AOD (Acoustic OpticalDeflector), which are employed in the modulator 83, on the basis of themodulating signal by outputting the signal to the modulator 83.

During the cutting process, in the cutting unit 74, the substraterotator/conveyor 85 drives the glass substrate 101 into rotation at aconstant linear velocity and, while the glass substrate 101 is beingdriven as it is, slides the glass substrate 101 by a distance equal to apredetermined track pitch in order to create a spiral track on thesurface of the glass substrate 101.

At the same time, the laser beam radiated by the laser beam source 82 ismodulated by the modulator 83 into a modulated signal based on themodulating signal received from the signal processor 81, and themodulated signal is radiated to the photo resist surface of the glasssubstrate 101 by way of the cutting head 84. As a result, the photoresist is cut out due to a light-sensitivity effect to form a groovewith a wobbling shape representing the modulating signal.

The controller 70 controls the cutting operation of the cutting unit 74and, while monitoring a signal generated by the sensor 86, controls theprerecorded-information generator 71, the address generator 72 and theswitching unit 73.

At the beginning of the cutting process, the controller 70 requests thecutting unit 74 to take the slide position of the substraterotator/conveyor 85 as an initial value so that the cutting head 84starts the radiation of the laser beam from the innermost circumference.Then, the controller 70 drives the cutting unit 74 to start an operationto drive the glass substrate 101 into rotation at a CLV and an operationto slide the glass substrate 101 by a distance equal to a track pitch of0.35 μm in order to create a groove.

In this state, the prerecorded-information generator 71 is driven togenerate prerecorded information used as shipping-time information andsupply the information to the signal processor 81 by way of theswitching unit 73. In addition, the laser beam source 82 is driven tostart the operation to output a laser beam whereas the modulator 83 isdriven to modulate the laser beam on the basis of the modulating signalreceived from the signal processor 81 in order to carry out a cuttingprocess to create a groove on the glass substrate 101. The modulatingsignal is an FM code modulation signal representing the prerecordedinformation. In this way, a cutting process is carried out to create agroove like the one shown in FIG. 3B in an area to be used as the PBzone.

As the signal generated by the sensor 86 indicates that the cuttingprocess to create a groove has reached an area to be used as the RWzone, completing the creation of the groove in the area to be used asthe PB zone, the controller 70 changes over the switching position ofthe switching unit 73 from a pole for the prerecorded-informationgenerator 71 to a pole for the address generator 72, and drives theaddress generator 72 to sequentially generates addresses.

In addition, the substrate rotator/conveyor 85 is driven to reduce thesliding speed of the glass substrate 101 so that a groove having a trackpitch of 0.32 μm is created on the surface of the glass substrate 101.

In this state, the address information generated by the addressgenerator 72 is supplied to the signal processor 81 by way of theswitching unit 73. In addition, the modulator 83 is driven to modulatethe laser beam generated by the laser beam source 82 on the basis of themodulating signal received from the signal processor 81 in order tocarry out a cutting process to create a groove on the glass substrate101 by using the modulated laser beam. In this case, however, themodulating signal is an MSK modulation signal representing the addressinformation.

In this way, a cutting process is carried out to create a groove likethe one shown in FIG. 3A in an area to be used as the RW zone.

As the signal generated by the sensor 86 indicates that the cuttingprocess to create a groove has reached the end of a lead-out zone,completing the creation of the groove in the area to be used as the RWzone, the controller 70 ends the cutting process.

By carrying out the operations described above, an exposure portioncorresponding to the wobbling grooves in the PB and RW zones on theglass substrate 101 is created.

Thereafter, processing such as a development process and anelectrocasting process is carried out to produce a stamper to be usedfor mass production of the disc described above.

8. Modified Versions

The description given so far explains an embodiment implementing a discas well as the embodiment's disc drive apparatus and disc-manufacturingmethod. However, the scope of the present invention is not limited tothe embodiment. That is to say, it is possible to make a variety ofchanges not deviating from the range of the present invention to theembodiment.

In the embodiment, while user data is recorded as phase change marks,any technique of recording user data can be adopted as long as thetechnique is of the rewritable or write-once type. For example, thepresent invention can also be applied to a disc or a disc driveapparatus adopting the magneto-optical recording technique or the dyerecording technique.

In addition, in the embodiment, shipping-time information is subjectedto a bi-phase modulation process. However, the shipping-time informationcan also be subjected to the same modulation process as user data. Inthe case of the embodiment described above, for example, since the RLL(1, 7) PP technique is adopted in a modulation process for user data,the shipping-time information can also be subjected to a modulationprocess adopting the RLL (1, 7) PP technique.

1. A disc recording medium comprising: a data area with a first wobbledgroove recorded in advance, in or adjacent to first data configured tobe recorded by marks, and in which a second wobbled groove is formed torepresent second data; and a reproduction-only area, in which a thirdwobbled groove is formed to represent third data, wherein said firstdata is configured to be recorded by adoption of a first modulationtechnique, corresponding to a first error-correction block structure;said second wobbled groove is wobbled by adoption of a second modulationtechnique; and said third wobbled groove is wobbled by adoption of athird modulation technique, including a second error-correction blockstructure based on a first correction coding for said firsterror-correction block structure.
 2. A disc recording medium accordingto claim 1: wherein: said first error-correction block structure andsaid second error-correction block structure are decoded using a sameerror-correction method.
 3. A disc recording medium according to claim 1wherein: said first error-correction block structure comprises a firstframe structure, a first sub-block structure comprising first errorcorrection codes and a second sub-block structure comprising seconderror correction codes; and said second error-correction block structurecomprises a second frame structure, a third sub-block structurecomprising first error correction codes and a fourth sub-block structurecomprising second error correction codes.
 4. A disc recording mediumaccording to claim 1 wherein: said second data and said third data arerecorded along the first wobbled groove; said first data is recorded asa rewritable recording technique of recording phase change marks onto atrack implemented as or adjacent to said first wobbled groove.
 5. A discrecording medium according to claim 1 wherein: said second data and saidthird data are recorded along the first wobbled groove; said first datais recorded as a rewritable recording technique of recordingmagneto-optical marks onto a track implemented as the first wobbledgroove.
 6. A disc recording medium according to claim 1 wherein saidthird data recorded onto said reproduction-only area includes addressinformation.
 7. A disc recording medium according to claim 1 wherein: arecording density of said third data is made less dense than a recordingdensity of said first data; a number of correction codes in said firsterror-correction block structure is set at a multiple of m; and a numberof correction codes in said second error-correction block is set at n/mtimes the number of correction codes in said first error-correctionblock, so that a data-piece count in said second error-correction blockstructure is also n/m times a data-piece count in said firsterror-correction block structure, where notations n and m each denote apositive integer.
 8. A disc recording medium according to claim 7wherein the value of m is a power of two.
 9. A disc recording mediumaccording to claim 7 wherein the value of n is
 1. 10. A disc recordingmedium according to claim 3 wherein: a recording density of said thirddata is made less dense than a recording density of said first data; anumber of first correction codes composing the first sub-block structureis set at a multiple of m; and a number of first correction codescomposing a third sub-block structure is set at n/m times the number ofcorrection codes composing said first sub-block structure, so that adata-piece count in said third sub-block structure is also n/m times adata-piece count in said first sub-block structure where notations n andm each denote a positive integer, whereas a number of second correctioncodes composing a second sub-block structure is set at a multiple of p;and a number of second correction codes composing a fourth sub-block isset at q/p times the number of correction codes composing said secondsub-block structure, so that a data-piece count in said fourth sub-blockis also q/p times a data-piece count in second sub-block where notationsp and q each denote a positive integer.
 11. A disc recording mediumaccording to claim 10 wherein the value of m is a power of two.
 12. Adisc recording medium according to claim 10 wherein the value of n is 1.13. A disc recording medium according to claim 1 wherein respectiveblock lengths of said first error-correction block structure and saidsecond error-correction block structure are each set at such a valuethat blocks can be recorded in a circle of said track on said disc. 14.A disc recording medium according to claim 1 wherein a number of framesin said first error-correction block structure and a number of frames insaid second error-correction block structure are each set at a valueabout equal to a data-piece count in said error correction codes.
 15. Adisc recording medium according to claim 3 wherein a number of frames insaid first error-correction block structure and a number of frames insaid second error-correction block structure are each set at a value atleast about equal to a sum of a number of first correction code wordsand a number of second correction code words.
 16. A disc recordingmedium according to claim 3 wherein said second frame structure includesa synchronization signal in a data portion corresponding to said thirdsub-block structure and also includes an address unit number in a dataportion corresponding to said fourth sub-block structure.
 17. A discrecording medium according to claim 3 wherein: said second framestructure includes a synchronization signal in a data portioncorresponding to said third sub-block structure; said synchronizationsignal is from one of a plurality of different signals so thatconsecutive second frames are different each other.
 18. A disc recordingmedium according to claim 3 wherein: said second frame structureincludes a synchronization signal in a data portion corresponding tosaid third sub-block structure; and said synchronization signalincludes: a unique synchronization pattern comprising a bit string neverobtained as a result of a modulation process adopting said thirdmodulation technique; a synchronization ID obtained as a result of amodulation process adopting said third modulation technique; and aparity field for increasing a code distance between said synchronizationsignals.
 19. A disc recording medium according to claim 1 wherein aframe for linking is added to said first error-correction blockstructure as well as to said second error-correction block structure.20. A disc recording medium according to claim 1 wherein a frame forlinking is added to said first error-correction block structure, but noframe for linking is added to said second error-correction blockstructure.
 21. A disc recording medium according to claim 1 wherein saidfirst modulation technique described above is an RLL (1, 7) PPtechnique, said second modulation technique is an MSK modulationtechnique, and said third modulation technique is a bi-phase modulationtechnique.
 22. A disc recording medium according to claim 1 wherein saidfirst modulation technique is a same technique as said third modulationtechnique.
 23. A disc recording medium according to claim 1 wherein saidfirst and third modulation techniques are a RLL (1, 7) PP techniquewhereas said second modulation technique is an MSK modulation technique.24. A disc recording medium comprising: a data area, in which user dataand user control data are configured to be recorded by marks, and inwhich an ADIP wobbled groove is formed to represent pre-addressinformation (ADIP); and a reproduction-only area, in which a prerecordedwobbled groove is formed to represent prerecorded information andprerecorded control data, wherein, said user data is configured to berecorded by adoption of a RLL (1.7) PP modulation according to a userdata LDC block using RS (248,216,33) and said user control data isconfigured to be recorded by adoption of a RLL (1.7) PP modulationaccording to BIS block using RS (62,30,33); said ADIP wobbled groove iswobbled by adoption of MSK modulation using an error-correction blockusing nibble-based Reed-Solomon encoding RS (15,9,7); and saidprerecorded wobbled groove is wobbled by adoption of a bi-phasemodulation corresponding to a LDC block structure using said RS(248,216,33), having a size that is different from said user data LDCblock, and said prerecorded control data is configured to be recorded byadoption of a bi-phase modulation corresponding to BIS block using saidRS (62,30,33), whose size is different from said user control data's BISblock.